Hi,
If you've purchased B2M3, you also have access to B2M2.
For people who purchase it on the Unity Asset Store, B2M2 is included in the package.
For people purchasing it on our website, B2M2 is in their account.
For people who purchased it on Steam, they need to link their account with our website and they can get B2M2.
B2M3 is designed for PBR use and B2M2 is for working with traditional maps is a non PBR workflow.
Cheers,
Wes