Hi Mohammed,
Were you able to solve this? I too have a similar issue, with Windows Server 2012 R2 and the services accounts only being able to log in when given elevated administrator privileges. I'd like to know more about what group policies are required for the login agent to work.
The service accounts can log into the VMs manually without any issues.
The service account can log in via login agent only with Admin privileges.
Looking forward to hearing from you.
Cheers,
Liam