Hi @michalchecinski,
Thanks for getting in touch with us at Auth0 Community.
You can achieve a mandatory checkbox to approve terms and conditions quite easily with classic login via the mustAcceptTerms property.
The flow is similar to the GDPR suggested flow as documented here:
https://auth0.com/docs/secure/data-privacy-and-compliance/gdpr/gdpr-track-consent-with-lock
New Universal Login does not support this out of the box right now.
You may however use Redirect with Actions. In this case, you can create a Post Login Action that will redirect a user to your hosted page upon signing up. On that page, you will build a form where the user can provide additional details and consent to the Terms of Use. Once the information is collected, you pass this data back to the Action (see Resume the Authentication Flow paragraph) and allow the user to log in or deny access based on your conditions.
Warm regards.