There are a few steps to enable this process
If you have permissions on a site, click on the Settings icon on the top right and then select Site settings on the left menu. If you do not have these options then you do not have the permissions on the site you are trying to access
Scroll down to the area title "GDPR Sign-Up" and click the option for "GDPR Sign Up Enabled". The options will then allow a title and description to be added.
Once enabled, all users will be forced to sign up in order to continue using the site. They will see the following option once they've successfully entered credentials to login to a site. Users will not be able to continue to use a site unless they accept the policy
A record of the date and time and text they signed up to is stored and displayed at the bottom of their user profile as a read only value, indicating when they accepted the policy and what the text they signed up to was.