Sandboxing is not allowed

Hi,
Im in the process of buying a domain name, but i was just embeding a code in html app and instead of showing me the stream it said, “sandboxing is not allowed.”

i checked the code in the testing website, “https://support.wix.com/en/article/testing-your-html-code” and it was working fine there.

is it because i have not upgraded to premium yet?

Connecting a domain to a Wix website is a premium feature. This forum is dedicated to Corvid. I suggest you contact Wix support team for this as they will be able to help you better.