You need a Visforms Subscription if you want to use this feature.
We are happy to announce that as of today - February, 25th, 2022 - all our major Joomla extensions Spambotcheck, Visforms and Visforms Subscription are also available for Joomla 4 To be available. This completes the migration of our software products for Joomla 4.
Migration instructions are available here:
We recommend using the Documentation for Joomla 4!
It is more up-to-date and extensive. Most of it applies retrospectively to Joomla 3.