How do I move my preexisting music library from my iPhone to my MacBook Pro without paying iTunes for the privilege to access the music that is already mine?

I want to put my iPhone’s music library, which originates from my old MacBook that is damaged and inaccessible, into the MacBook Pro that I now have. However, the only option is to synch up to the current computer and to move my files in the opposite direction from that which I need. The music files in my MacBook were decimated by a “cleanup" app I purchased from the app store to remove duplicate files that wound up not actually being duplicates at all (a separate issue, but the reason it’s essential that I don’t lose more). The synch menu appears to only allow a one way transfer from computer to phone, which is the opposite direction I need to transfer. Also, I have two separate libraries, one from my old computer that broke and one from my current one which replaced it, but I’m only permitted to synch my MacBook with one of them. It is not only a confusing and time intensive process to try to navigate, but it also appears that I have to shell out more of my hard earned money to pay iTunes an ongoing fee for the “privilege” of transferring the music that I already paid for amongst the devices that I also already paid a lot of money to purchase.I hope this is not the case, and someone can show me how to get my iPhone’s music onto my MacBook Pro.