When you add your license key to wp-admin->Inbound Pro->Settings and press ‘Rebuild Permissions’. What does the error message say?
Some hosts do have problems with connecting to our API Key. When this happens, if there’s not a clear solution provided by contacting your hosting provider, I usually am unable to help and have to offer a refund. It’s never an issue I can take care of on my side though.
I don`t get a error message. When I have inserted the api key and clicked on rebuild permission, then field are displaying with red color around that api field, and at right a red cross icon, which indicated that api key are not accepted.
I have inserted this api key on another site and exactly same hosting provider and server, and without any problem.
For me it seems like the api key are not correct compared to the license/plan I have purchased. Could it be that I have received an api key for the free plan, instead of the plan I have signed up for / purchased?