In a Nintex Automation Cloud Workflow, I am trying to get a token with a “Call a web service”-action with this endpoint:
https://login.microsoftonline.com/myTenantId/oauth2/v2.0/token
Request Type is HTTP Post
Request Headers are: Content-Type:application/x-www-form-urlencoded
Request content:
grant_type=client_credentials
client_id=myAppId
client_secret=myAppsecret
scope:https://myTenant.sharepoint.com/.default
I get this Response: {"error":"unsupported_grant_type","error_description":"AADSTS70003: The app requested an unsupported grant type

My App-Registration on Azure has Sites.Selected Permissions:

And the permission has been granted to a specific Site by Grant-PnPAzureADAppSitePermission
This App has a valid Client-Secret.
Public Clientflows are allowed.
Why do I get “unsupported grant type”?
What am I missing here?
Any help is appreciated, thanks!