ADFS Administration - nordvall/TokenClient GitHub Wiki
OAuth Clients can be registered with PowerShell on the ADFS server. The command is called Add-AdfsClient.
Add-AdfsClient [-ClientId] <String> [-Name] <String> [[-RedirectUri] <Uri[]> ] [-Description <String> ]
I can not find anywhere to register or generate Client secrets, so I suppose that the client credentials grant will not work.