RapidAPI and OPUS API subscription, but it doesn't let me sign up.

Hi, 
I am trying to set up to use Houdini-MCP and OPUS integration. 
https://github.com/capoomgit/houdini-mcp?tab=readme-ov-file

And I tried to create an account and sign up for RapidAPI and OPUS API subscription, but it doesn't let me sign up.
It keeps saying my emails(I tried all four emails) are validated. 
Is this the only way to obtain your RapidAPI key to use Houdini-mcp?

Thanks