Logic Pro Query.

I have an iMac (Retina 5K, 27-inch, Mid 2015)Big Sur 11.7.4. (called Ruth's Mac. My partner) I cannot upgrade the operating system any higher. My iMac is in great condition but I want to install Logic Pro. Apparently, I cannot. The Apple site says 11.5 iOS is fine but then, if you try to get a free trial or a purchase, it changes to a much higher iOS.

Is there no way I can, legitimately, get hold of a copy of Logic Pro that will work on this excellent computer? It seems mad. I am happy to buy it but can't. Any fairly recent version would do.

Any ideas?

Thanks Apple Community