https - facebook link - zohosites subdomain error

Good day all,

So Here I am setting up an app in facebook and using your free site to link to that app.
I setup the canva, works like a charm.
I tried my url using the https://
Works like a charm outside of the site.

I try the app and i get: MORE_THAN_MAX_LENGTH

Now i tried talkin to facebook.
Nothing.
Is there additional security setup on zoho that prevents the post request from being received or sent to facebook?

Now here is the thing. I have tried other sites, and it appears to work fine. Some do have restrictions that prevent it from opening in a iframe... But i do not see that being an issue here....

So I am confused...