hello @Andre, welcome to the Tulip community!! it would be great if you could introduce yourself at: Welcome to the Community, let's meet!!
have you investigated selecting the Users you’d like to display from a Dropdown Single Select??
as you can see above, you can select individual Users you’d like to include in the options list.
but to access the User’s Emails, you can use a Trigger similar to this:
let me know if I understood your question!!