ToME: the Tales of Maj'Eyal

I own the steam version of the game and bought both DLC on there. Is there some way to enable that DLC on the standalone version?

I only own the standalone version so I'm not exactly sure where the steam dlc are stored, but you should be able to just copy them from there to the addon directory of the standalone version

There should be a button somewhere in your te4.org profile that will do it.