Google Sites - Chat isn't working

[The Hunters]

So I am using Google Sites as my web provider and not using WordPress. When I try to embed the chat URL I get the following error of "can't embed due to provider site permissions. URL will be display as a text link".

I have tested the URL from 3cx chat by pasting it into a browser and it works. Just can't get it to work within my website host/developed on Google Sites.

Any advice? Fix? something I am missing on either platform?

Thanks in advance.