••• I'm looking to download/transfer the photos from my TM file to my Photos app.
Photos cannot open a library as part of the Time Machine backup. And it cannot work with a library that is stored on a drive, that is used by Time Machine.
Run Time Machine to restore the iPhoto Library from the Time Machine backup. if you simply copy the library out of the backup, it may still not work. Time Machine needs to recreate the links in the library package. This document describes, how to restore an iPhoto Library from a Time Machine backup: https://support.apple.com/en-us/HT202321
Once the library has been restored to your Pictures folder, you can drag it onto the Photos icon to convert it to a Photos Library or open it in iPhoto 9.6.1, if you still have this version of iPhoto installed.