Where can I get the Compatibility Matrix for Remedy 20.02?

This knowledge article may contain information that does not apply to version 21.05 or later, which runs in a container environment. Please refer to Article Number 000385088 for more information about troubleshooting BMC products in containers.
 

You can check the BMC SOLUTION AND PRODUCT AVAILABILITY AND COMPATIBILITY UTILITY (SPAC) in the Support site.
Link: https://docs.bmc.com/docs/compatibility/

There it will be listed all the requirements for AR System.
To get the actual Compatibility Matrix, you need to search for the required product

Once you select the required version, you will get the detailed information as show in the following image:

Also, you can get compatibility matrix in PDF format. See BMC Remedy ITSM Suite compatibility matrix