Hosting domain registered to client

I have a client that has already registered their domain with dreamhost, now I need to host it on my dreamhost account (they registered domain only I will host them for the time being on my account) and have them grant me administrator access to start developing their wordpress wite. I’ve never had to do this before and I feel like a noob. Can someone help me with a step by step.

Have you tried to add the domain under

“Add new domain”

An option may be for your client to give access permissions to their web space to you:

Then when they want to take back ownership they can just delete you as a user.

Thank you for taking the time to help me- I got it all sorted out.