Remote desktop manager for mac error 131084

I am a long-time RDM user on Windows. I am in the process of switching to OSX and I downloaded RDM for mac and imported my session list, but none of the sessions works unless I choose external and let the default RDP manager open the session. That's not optimal, but it also won't use the credentials I pass in. I saw another post that said something about clicking a box to not manage RDP Certificates internally, but I can't find that setting anywhere. Help?!?