Removed service packages in the sample package folder, set manifests to target the package manager.

Assets/Scripts/Auth/SubIdentity_Authentication.cs

 
         private async void DoSignIn(Action onSigninComplete)
         {
-            await UnityServices.Initialize();
+            await UnityServices.InitializeAsync();
             AuthenticationService.Instance.SignedIn += OnSignInChange;
             AuthenticationService.Instance.SignedOut += OnSignInChange;
 

Packages/manifest.json

     "com.unity.ide.visualstudio": "2.0.9",
     "com.unity.ide.vscode": "1.2.3",
     "com.unity.nuget.newtonsoft-json": "2.0.0",
+    "com.unity.services.authentication": "1.0.0-pre.4",
+    "com.unity.services.core": "1.0.0",
+    "com.unity.services.lobby": "1.0.0-pre.2",
+    "com.unity.services.relay": "1.0.0-preview.1",
+    "com.unity.transport": "1.0.0-pre.1",
     "com.unity.ugui": "1.0.0",
     "com.unity.modules.ai": "1.0.0",
     "com.unity.modules.androidjni": "1.0.0",
     "com.unity.modules.vr": "1.0.0",
     "com.unity.modules.wind": "1.0.0",
     "com.unity.modules.xr": "1.0.0"
-  }
+  },
+  "scopedRegistries": [
+    {
+      "name": "Candidates",
+      "url": "https://artifactory.prd.cds.internal.unity3d.com/artifactory/api/npm/upm-candidates",
+      "scopes": [
+        "com.unity.services.lobby",
+        "com.unity.services.relay",
+        "com.unity.services.authentication",
+        "com.unity.services.core",
+        "com.unity.transport"
+      ]
+    }
+  ]
 }

Packages/packages-lock.json

       "url": "https://packages.unity.com"
     },
     "com.unity.services.authentication": {
-      "version": "file:com.unity.services.authentication",
+      "version": "1.0.0-pre.4",
-      "source": "embedded",
+      "source": "registry",
-        "com.unity.services.core": "1.1.0-pre.4",
+        "com.unity.services.core": "1.1.0-pre.8",
-      }
+      },
+      "url": "https://artifactory.prd.cds.internal.unity3d.com/artifactory/api/npm/upm-candidates"
-      "version": "file:com.unity.services.core",
-      "depth": 0,
-      "source": "embedded",
+      "version": "1.1.0-pre.8",
+      "depth": 1,
+      "source": "registry",
-      }
+      },
+      "url": "https://artifactory.prd.cds.internal.unity3d.com/artifactory/api/npm/upm-candidates"
-      "version": "file:com.unity.services.lobby",
+      "version": "1.0.0-pre.2",
-      "source": "embedded",
+      "source": "registry",
       "dependencies": {
         "com.unity.services.core": "1.1.0-pre.4",
         "com.unity.modules.unitywebrequest": "1.0.0",
         "com.unity.modules.unitywebrequestwww": "1.0.0",
         "com.unity.nuget.newtonsoft-json": "2.0.0"
-      }
+      },
+      "url": "https://artifactory.prd.cds.internal.unity3d.com/artifactory/api/npm/upm-candidates"
-      "version": "file:com.unity.services.relay",
+      "version": "1.0.0-preview.1",
-      "source": "embedded",
+      "source": "registry",
       "dependencies": {
         "com.unity.services.core": "1.1.0-pre.4",
         "com.unity.modules.unitywebrequest": "1.0.0",
         "com.unity.modules.unitywebrequestwww": "1.0.0",
         "com.unity.nuget.newtonsoft-json": "2.0.0"
-      }
+      },
+      "url": "https://artifactory.prd.cds.internal.unity3d.com/artifactory/api/npm/upm-candidates"
     },
     "com.unity.sysroot": {
       "version": "0.1.19-preview",
       "url": "https://packages.unity.com"
     },
     "com.unity.transport": {
-      "version": "file:com.unity.transport",
+      "version": "1.0.0-pre.1",
-      "source": "embedded",
+      "source": "registry",
-      }
+      },
+      "url": "https://artifactory.prd.cds.internal.unity3d.com/artifactory/api/npm/upm-candidates"
     },
     "com.unity.ugui": {
       "version": "1.0.0",

ProjectSettings/PackageManagerSettings.asset

   m_Script: {fileID: 13964, guid: 0000000000000000e000000000000000, type: 0}
   m_Name: 
   m_EditorClassIdentifier: 
-  m_EnablePreReleasePackages: 0
-  m_EnablePackageDependencies: 0
+  m_EnablePreviewPackages: 1
+  m_EnablePackageDependencies: 1
-  m_SeeAllPackageVersions: 0
   oneTimeWarningShown: 1
   m_Registries:
   - m_Id: main
     m_IsDefault: 1
     m_Capabilities: 7
-  m_UserSelectedRegistryName: 
+  - m_Id: scoped:Candidates
+    m_Name: Candidates
+    m_Url: https://artifactory.prd.cds.internal.unity3d.com/artifactory/api/npm/upm-candidates
+    m_Scopes:
+    - com.unity.services.lobby
+    - com.unity.services.relay
+    - com.unity.services.authentication
+    - com.unity.services.core
+    - com.unity.transport
+    m_IsDefault: 0
+    m_Capabilities: 0
+  m_UserSelectedRegistryName: Candidates
-    m_Modified: 0
-    m_UserModificationsInstanceId: -822
-    m_OriginalInstanceId: -824
-  m_LoadAssets: 0
+    m_Original:
+      m_Id: scoped:Candidates
+      m_Name: Candidates
+      m_Url: https://artifactory.prd.cds.internal.unity3d.com/artifactory/api/npm/upm-candidates
+      m_Scopes:
+      - com.unity.services.lobby
+      - com.unity.services.relay
+      - com.unity.services.authentication
+      - com.unity.services.core
+      - com.unity.transport
+      m_IsDefault: 0
+      m_Capabilities: 0
+    m_Modified: 0
+    m_Name: Candidates
+    m_Url: https://artifactory.prd.cds.internal.unity3d.com/artifactory/api/npm/upm-candidates
+    m_Scopes:
+    - com.unity.services.lobby
+    - com.unity.services.relay
+    - com.unity.services.authentication
+    - com.unity.services.core
+    - com.unity.transport
+    m_SelectedScopeIndex: 0