I just performed the update using the instructions here and additional specifics from the same forum members who also post over on the Outback forum. The update applied to a 2023 Ascent Touring.
Can also confirm you only need the directory and file on the USB stick that applies to your trim level. That's all I loaded. To future updaters, set up the directory structure on the USB for your trim level and only download the single ALLUPD-NAVI applicable. To make sense of this...read the Outback forum thread. Neither Chrome or Explorer keeps those files in a single zip containing the directory structure downloading from Google Drive. Why...don't know, maybe the file size.
I followed the TSB to the letter. I did experience the "RARE case of “Software update setup is initializing…” message" shown in Appendix A of the TSB. Followed those instructions, with the car idling, and after about 15 minutes (didn't time it), the "initialization complete" message showed up.
Special thanks to the members posting and hosting the updates!