Currently, when you request a document you can either select an existing user OR type in a new e-mail address. If you enter a new e-mail address, Workfront creates a reviewer licenced user behind the scenes.
Another less obvious difference is if you enter a new e-mail address, the link in the e-mail that gets sent include a 'tokenID' which means the recipient doesn't need to log in to upload the document. However, after the first time all subsequent requests will require a login (as that e-mail address is now associated with a user).
It would be fantastic to have a 'require login' checkbox (defaulted to ticked so that functionality is unchanged for current users) .
If the tickbox is ticked, then the tokenID is not included in the link even if it's a new user (instead they get the login screen, and can use 'forgot password' to set their initial password).
If the tickbox is clear, then the tokenID is included even if the user is an existing user. If they try to browse anywhere else (they would have to manually change the URL, as there are no links on the page to navigate anywhere else) they would need to log in first.
Note that all of this is existing functionality. All we are asking for is a manual control, rather than automatic behaviour based on if it's a new user or not.