Running someone's else account

Hello, I am a PR specialist and I would like to create an IMDb Pro account for my client to run that for him. My question is how can I create this account to be acclaimed as him - should I open the new account from his email address or can I do it with my email? If I put my email while registering, how can I pick his profile as the one I manage/I pay for? My task is to take care about his page on IMDb Pro, changing a picture and making it fully up to date. Can I do that with the account fully created by me on an agency email?