How to update AMD Radeon R9 M295X drivers to latest version on iMac from Late 2014 running Bootcamp

I'm trying to have some light gaming on this iMac but keep getting this minimum version requirement. When I navigate over to the AMD website with all the available bootcamp drivers I cut off at version 20.45.40

How do I get the latest version?

My iMac details

iMac 27inch 5k AMD Radeon R9 M295X