How do I add a sign up form to a Wix Site?

Wix supports using the Slide-Out Forms, it does not currently support using the Exit-Pop Up form.

How to add a Slide-Out Form code to your Wix Site:

When adding the Slide-Out Embed code to your wix site. You will be adding the code to an HTML section. For details from Wix on how to use an HTML section click here: Wix Help Center on HTML Code