external api script invalid due to domain

Hello, my client is switching from wordpress to Wix, but utilizes this internal (necessary) api for their purchases. The way it validates the key is through the domain.

their docs give us

I’ve tried making a blog post with html, then publishing it: doesn’t work
I’ve tried adding it as code within the dev tools: doesn’t work
All the keys generated are the wix preview pages so I am confused why it’s not working here but it is working on wordpress

thank y’all!

Do you see anything in the console?