Arc for Sql Server upload response status: Forbidden.

Hello all,
I have an issue with adding our SQL Server to Azure Arc
The Azure Connected Agent (azcmagent) installed fine - and the extension installed aswell.

However, checking the logs i get following error...

[AzureUpload] Arc for Sql Server upload requestId: 718ca3d0-ffd7-4c40-ad1f-ccd8bc43ef41, uri: https://san-af-westeurope-prod.azurewebsites.net/api/subscriptions/<<subscription_ID_dedacted>>/resourcegroups/management/providers/Microsoft.AzureArcData/sqlServerInstances/<<SERVERNAME>>?api-version=2021-08-01  
[AzureUpload] Arc for Sql Server upload response status: Forbidden.  
[AzureUpload] Arc post request failed with error: Forbidden message: {"ErrorDescription":{"ErrorCode":6,"Message":"The user has no access to the provided Azure resource."},"ResponseUrl":null}  

I searched the internet but only found this.
https://video2.skills-academy.com/en-us/sql/sql-server/azure-arc/connect-at-scale?view=sql-server-ver15&tabs=windows#server-managed-identity-has-insufficient-permissions

things i already did:

• i registered the Microsoft.AzureArcData and Microsoft.HybridCompute resource providers with the resource group
• i added the computer to the Azure Connected SQL Server Onboarding Role
• checked firewall settings and connection to internet
• -just reinstalled the arc agent and sql extension

No Proxy

any help would be appreciated
thanks