The domain which you have entered belongs to a different deployment/region

The domain which you have entered belongs to a different deployment/region

Hello. I'm trying to register a new account for my client. I sent him a referral code, and we're trying to set up his account using that referral code. The first time we tried to set it up, we got the message that says:

"The username which you have entered belongs to a different deployment/region"

We thought it was an error, so we tried to start over. And now every time we try to set it up, we get this error:

" The domain which you have entered belongs to a different deployment/region"

I've emailed support about this and have not received any response. Please help us get this set up.

The domain is www.technologysolutionsprovider.com.

Thank you.