transferring music from mac os x 10.6.8 to mac high sierra 10.13.6
I'm going nuts, guys. I've tried transferring music from iTunes on my old mac (os x 10.6.8) to my new one (high sierra 10.13.6) and nothing but weird things have happened. Not only do I still not have the old music on my new computer (after trying with migration assistant and apple music) but now I get an incessant message saying "The iTunes Library file cannot be saved A duplicate file name was specified" that pops up repeatedly no matter what I do, even though iTunes seems to work fine. I've also notices that files I keep deleting from my library show up again every time I open iTunes.
I'm ready to restore iTunes to factory settings, no loss for me there. But does anyone have any tips for how to move my music over from my old laptop? Please and thank you!
MacBook, 10.13