Can I provision ODB for an unlicensed user? and How?

This user has total access to my business ODB sharepoint database. 

He can add and suppress files alright. 

Yet, after Onedrive app install (latest version on MacOS) he gets a message that OBD cannot be reached. 

When I check my ODB admin panel it says that ODB wasn't provisioned for this user. 

Can I do this for him and how?