If you purchased a download it will be Windows only. It is possible to buy the boxed product from retailers like Amazon, Costco etc. which comes with disks for both Windows & Mac. After purchase you can still download the software (many computers now come without a disk driver) and simply activate with the serial number from inside the box.
You can get PSE 2020 as a 30 day fee trial should you wsh to test the software before purchasing an upgrade.