Migrating a very large iTunes library to the "Music" app on Macs (not PC's)

Hello iTunes gurus,

I have tens of thousands of tracks in my iTunes library running off of external memory adding up to a little less than 120 GB of data, with several dozen playlists & smart playlists (some within playlist folders & some smart playlists referencing other playlists & smart playlists), running off of a 12-year old Apple laptop running OS 10.11.06 & iTunes 12.8.2.3. I'm trying to migrate it all to a less old (not new) Apple laptop running OS 10.15.7 & Music 1.0.6.10. I will have to keep my music library on external memory cause it doesn’t fit in the newer laptop, which is fine. How do I migrate it ALL, AND preserve all my playlists, smart playlists, ratings, loves, play counts & last played data? (I don’t care about the skip data.) I can get the music files transferred with all their info tags except what I just listed here. And nearly all the smart playlists are incomplete. And I can’t seem to get any of the ratings, loves, play counts & last played data to transfer over. I have put countless hours into fine-tuning those playlist, smart playlist, ratings & loves. I just can’t lose that data. Yes, I have organized & consolidated the entire library (in that order, which took almost a full day), but the iTunes Music Library.xml file is still located on the laptop’s hard drive, not my external memory. Not sure where the iTunes preferences file is located. And yes, I have backups of everything. And I do not want to use iCloud; I can't afford that much cloud data.

I read all I can find on this & experimented, but no luck. To start fresh I cleaned out the library on my newer "Music" app.

I tried the exporting & importing playlist functions, but it gives me an empty file. Does that function export ALL the playlists & smart playlists data or just one playlist at a time?

Again, more importantly, how do I migrate it all AND preserve all my playlists, smart playlists, ratings, loves, play counts & last played data? Thank you in advance for your expertise on this. (Please don’t send me links to how do it on a PC; I don’t have a PC. That’s all I can find in the Apple support communities & elsewhere, & it’s not sufficient.) HELP!