itunes library to music app

Hi I have just updated my Mac from High Sierra to Monterey and I have so far been unable move my 650 gb iTunes library from iTunes to the Music app I have tried the obvious ie holding down the option key to start Music then choosing the iTunes file it then asks again to choose file and I then select the itl file it proceeds to endlessly show loading.... on the first occasion I let it run for around 2 days on the second 3 days also I get a message that say's "AMPLibraryAgent quit unexpectedly" to be honest I'm becoming a little frustrated at a) how long it take (if it actually ever gets there and b) The lack of information/advise offered by Apple on how to carry out this procedure given their decision to remove IMO the perfectly good iTunes, given that I would really appreciate any advise or information that would help with my problem.