Merchant’s domain URL is broken

I followed the installation process and successfully connected to my Pinterest account. However, I got the dreaded “Merchant’s domain URL is broken” message

The URL is certainly not broken, but there isn’t any information on how to resolve this. Pinterest gives you 2 appeal chances. But I don’t know what needs to change. Pls help.

Thanks in advance!

The page I need help with: [log in to see the link]