How to add current page URL as a hidden field in ZOHO Campaigns SignUp Form

How to add current page URL as a hidden field in ZOHO Campaigns SignUp Form

Hello,

I am trying to add current page URL as a hidden field in ZOHO Campaigns Sign Up Form.

We have about 15 ebooks on our website, and I am wanting to have one ZOHO Campaigns list for "EBooks", and then segment the list into "Ebook 1" "E book 2" etc based on the page URL that the ebook signup was completed.

Firstly, is this possible? from reading some of the support docs, it seems it is (see below). I have created the form, added a hidden field called "URL" but cannot figure out how to populate that field automatically, and how to then segment the list by that field. Any help from ZOHO or the community would be much appreciated. Thanks!

https://help.zoho.com/portal/en/kb/campaigns/user-guide/signup-forms/creating-a-signup-form/articles/how-to-customize-signup-form#Edit_Field
"Mark as hidden field - When a contact tries to sign up through a form, the hidden fields auto-fill themselves. Later, you can filter the contacts based on hidden field and create segments to target a set of contacts."