[Broad Cast Plugin] Change URL

I have this Multisite - https://www.tum****ts.com/ its a multisite network and has a plugin on it called broadcast. I broadcasted this page to over 60 sites. In the bottom of this page it has a "book a class" button

tu******ts.com/oxford/our-programme/

This page is copied onto lots of other sites and linked so if change is made on one its made on more - this then means all the links are for the original site eg the national one - but if you want a link to go to a specific site you are on eg Oxford it needs to get the site URL. ie: tu****ots.com/oxford.

For templates it has this href="< ? php echo get_site_url(); ? >/book”, but I need to do this in the page builder but it doesn't work.

How can I get the link to replace in each site?

I found this but I don't think it will work - https://stackoverflow.com/questions/29233174/how-to-get-the-current-page-url-using-javascript-and-using-it-in-a-a-href-the/29233300