I have full permissions on Azure side and created a service account in Azure AD. After adding the client id, secret and tenant, my login is working. But when I tried to use Azure AD Matrix-based strategy, auto complete is not working and the logs is printing "WARNING: Do not have sufficient privileges to search related users or groups". 

I can add my username directly and the matrix strategy is working but if I wanted to use group, I don't know how to specify it. For this I planned to use the auto-complete.