I cannot invite people

Hi,
It gives me an error when inviting people to work on my translations. What is going wrong?

Hello @UASA

Do you use Free Plan → private project? If so, for this type only inviting vendors are available (resources → vendors).

Or, alternatively, you invite managers when you reached the available limit. Or maybe free trial has expired. Would you have a chance to double check and update me so I can clear my assumptions?