Upon making a new profile, I went in to help set up their password, and the button for creating a password is missing.

As an administrator, you would have to be logged out before you could create a profile for a new member.

After clicking on the new member's name, the JOIN HERE page appears. You click on "click here now to create your login!"

In the Member Wizard, Step 1 of 4: Contact Info, the Create Password box is just below the Alternate Email(s) box.

As an admin, you can add a new member on the Enter/Edit Classmates page - and then add details and/or profile data and answers if you wish. But the only way to add a password for a new member is to (at least temporarily) make them a hidden member - which then allows you to add a password, or log out and join as that member.