How do I transfer music from my vintage laptop to my macbook pro mid 2012?

Transfer the music files to an external USB HDD. Connect the drive to your new computer and restore the files.

If music library is small enough to store on USB memory, copy them on it and restore them on MacBook Pro.

Or copy the library via File sharing.

If your vintage laptop is a Mac, try target disk mode:

https://support.apple.com/en-us/HT1661

Ciao.