Mastodon rel="me" verification code

Hi, I am new here and I have a small question about the rel="me"   verification code.

To have the site 'verified' on Mastodon we need to insert the code which of course has a link back to the Mastodon profile.

I was trying to add this to my site but I am getting an error.

Thank you in advance for your support. 

I only have the cheapest Squarespace plan so I can’t do this. I am hoping Squarespace will add this feature and also direct posting.