Fun game, really enjoyed it! I think more intuitive requirements/combos would certainly help - it's hard to wrap my head around why a mail wagon requires a 1, 2 and food wagon which makes it difficult to recall during gameplay. More feedback when scoring would be nice too, it took me a few rounds to notice I wasn't actually playing properly and hadn't met any of the requirements!
The carts lighting up green when the requirements were met was a nice touch. Good work overall!