Have Plex on Windows, but switching to Linux

For the past year, I have been uploading my movies to a Synology NAS, and have the Plex Media Server installed.

However, I will soon be switching from Windows to Linux (because I don’t want to move to Windows 11).

Will I need to reinstall Plex on my Linux machine, or is it running on my NAS? (I’m assuming it’s on my Windows PC, because I previously downloaded the Windows version.)

If I have to reinstall a Linux version, will it find all my movies currently on my NAS?

Will I lose all the customizations I made in Plex (such as Collections, and editing the descriptions of some movies)?

If I’m reading your post correctly, you would not lose your movies, you just need the new Plex install to point to the correct location.

Its possible to save all the customizations if you copy the Plex data dir from the windows pc
to the Linux pc

I’d suggest reading this a few times until it makes sense and take notes.
https://support.plex.tv/articles/201370363-move-an-install-to-another-system/

You need to figure this out. Go here to look at servers you admin on your account

https://app.plex.tv/desktop/#!/settings/devices/pms

There may be old ones but the block with whatever is your current server should say what it is running on.