Legal accept not working with external cache

I'm using this module on a site with Varnish.

There are problems with legal_accept path.
When Varnish is enabled, when a user try to login (after a legal change), the legal_accept page returns a 403 error, forbidden.
If I exclude Varnish, legal works, so there is something that doesn't work.
Could be the cookie?
Looking at the browser console, there are legal's cookie..

Thanks