Unable to retrieve from HDD despite inserting into external enclosure

Doing a friend a favor by doing some troubleshooting. I have an old IDE 3.5" Maxtor HDD in an old Dell Dimension. The computer is no longer able to boot up XP for no reason. It goes through the motions of loading the native Dell stuff, but then I'm prompted with starting the computer in Safe Mode, Normal, etc. Once I select an option the computer goes to the blue screen of death.

(I put the HDD in another spare Dell Dimension that works, and still encountered the same issues.)

I put the HDD into an external enclosure, and I'm able to view all of the files and folders. Unfortunately, the primary user folder is locked, and I'm unable to access all of his key docs, photos, etc. I suspect that is happening because the drive is meant to be the bootable drive as well.

My goal is to simply retrieve the valuable files under the User Folder. Can't find an option to unlock that folder when I view it in the external enclosure.

Any recommendations?