Unable to Sign Up for Sign Trial for Web Forms

OK - I want to look at using Sign to create some web forms for our website, but ideally want to test it out first to make sure it does what I need. Clicked on the free small business trial button, and it says 'We have identified that you already have an active account with Adobe Sign and therefore you are not eligible to sign up for the trial'. I don't as far as I'm aware, but I do have an Acrobat Pro DC subscription which it says includes Sign - but it doesn't do web forms - option doesn't appear in either the app or online, and when I try to go to the Sign url it flips me straight on Acrobat DC online.

It really shouldn't be this hard ! Is there a simple way to sort, or should I abandon the whole thing and look at Docusign et al ?