Looks like this little gem is available on GoG -
https://www.gog.com/game/majesty_2_collection
20 USD seems a bit steep, but it allegedly includes the expansions, though I note you say those are disabled.

I read through the user reviews, including one as recent as Nov 2018, and nobody says anything about expansions not working, so perhaps GoG has worked their unique magic upon this. They are indeed very good at reviving old games.

Interestingly enough, when I look this up on Steam, I see an add to cart button, with a price of $9.99 for the base game, or $14.97 with the three expansions. This doesn't mean you were wrong to say there is no buy button; I am in Argentina, and Steam has regional pricing and availability

In any case, thanks for bringing this to my attention. I love old games :)