If you are testing your logins and your members are being redirected to a 404 Page not found page, you may not have specified a hidden content folder. Here is how to fix that!
Step 1: Go to the power-ups page and scroll down and open the "Member-specific Pages" section.
Step 2: Type the name of the folder or CMS collection that contains all of your members' pages. Click anywhere to save. Now, when a user logs in they will be redirected to a page inside of that folder.