Sharing one account between two people is something most platforms do not allow, at least not in the way most people think. The account is meant to represent one individual, and having two people log in and send messages or submit work can confuse clients and break the platform rules. Some platforms like Upwork have a separate agency feature that lets a team work under one profile legally. Outside of that, sharing accounts can get both people suspended. Are you trying to work with a partner, and have you looked into the agency option?