Logic Pro on iMac won't update to 10.8, is stuck on 10.5.1

I'm using an iMac (27" display) and need to update the Logic Pro on this other person's computer from 10.5.1 to 10.8, but when I tried going to the Apple logo > App store and checked for updates, there were none. It's really frustrating for this person because it has limited functionality compared to Logic 10.8. How do I update it? Is 10.8 just not supported on a 27" iMac?

As for the system specs (if needed), here they are:

macOS Catalina

Version 10.15.7

iMac (Retina 5K, 27-inch, 2019)

Processor: 3GHz 6-Core intel Core i5

Memory: 16GB 2667 MHz DDR4

Graphics: Radeon Pro 570X 4 GB

Serial Number: H12C6HZRJV3X