Activating audiences to SFMC

Hello there, 

I have successfully created an audience in RTCDP and now wish to activate that audience to SFMC. I am following the documentation and understand that a mapping id needs to be created that matches the mapping id in the segment. I am wondering where in SFMC the mapping id attribute needs to created. I was trying to create it within the Profile Management tab but don't seem to have permissions to and had our SFMC admin try to create an attribute there but there may be additional licensing fees associated to adding more attributes there in the long run. Can you provide any insight on how to properly approach this? Thanks!