Hi there - a tip from me as a long time Mac/Logic user:
to those of you (like me) using OSX Sierra (12) or below:
Try logging in on another machine with OS HIgh Sierra or higher, OR make a small new partition/volume on your disk and install latest OS. THEN buy/download the app (Logic or Final Cut) from App store on that partition. You do not need to download, just get the confirmation that you have "bought" it....
THEN, on your Sierra or below partition, log in to App Store, try to download Logic/FCP - and you should get a message that gives you an option to download the latest compatible version (I'm stuck on 10.4.4 btw, latest Sierra-compatible).
DISCLAIMER: I have not tested this on this particular offering - BUT it worked when I needed an older version of Keynote. I "bought" it on a compatible machine, then went back to my old and got the possibility to download the latest compatible version. (Of course you need to use the SAME Apple ID when buying and downloading.)
Please correct me if I'm wrong - but if you're out of work anyway these days, give it a try and tell us how it went!