I already have msalup@cpsgrowthinstitute.com and want to create concierge@cpsgrowthinstitute.com

Every article I read says about "adding" an account, but if you are trying to actually create an account, the OP they send to concierge is, of course, useless, because the account does not exist. What is the solution? I've tried every search possible in the knowledge base. I can't believe something so simple can be so obscure.