I have an existing WODHub account can I use it

Absolutely!

Just choose the 'Sign-in' option to the left, and login with your existing account.

What is the domain about?

We host your services on our servers, initially you can access them on a subdomain of wodhub.com, but once you have signed up you can run all our services of your own website domain, like AcmeCrossfit.com for example.