It's fairly easy to run in Roll20! Upload your map image to the session and then under the "Collection" settings click "Show, Playing Cards, 54." This will add a deck you can deal from directly to your playspace. Then, as long as you give all the players drawing privileges and assign them a unique color, they can draw shapes over the map to claim buildings! Coloring in the buildings is definitely more satisfying, but drawing a circle or square in your player color works just as well. I hope this helps!