Getting started with Smush Pro

I've put in my credit card details and admin details.
Then I get this message even though the URL is correct:
"The URL you have entered is not accessible. Please check it's the correct domain then try again. If the issue persists, contact our 24/7 support"
Support live chat said I was number 1 and it would be 5 minutes.
Now I've been waiting 25 minutes and still nothing!
Just about to cancel and go elsewhere!