https
/support.apple.com/en-ca/HT201948
First make sure it has a 64bit processor as logic only runs on mac's with that.
OS X 10.11 or later, is required.
other than that, lots of ram always helps DAW software, but getting an older mac, means older HD probably, which will be slow for DAW stuff.
Basically people build the most monster high end PC's they can for audio work because it can and will use every available resource. cheaping out will only make the experience that much more painful. lol.