Creating Server Connection
If the Tasks feature layer is published to a standalone ArcGIS Enterprise Server as a REST feature service, then you need to create a server connection in ArcGIS Pro.
Enter the required URL and credentials.
For more information about connecting to an ArcGIS Enterprise Server from ArcGIS Pro, refer to: https://pro.arcgis.com/en/pro-app/latest/help/projects/connect-to-a-gis-server.htm