Newbie to Roll20 with a minor issue

We are a new group to Roll20. I purchased the Pro package and decided to use the Sunless Citadel add on for our first campaign. I successfully created the game with the add-on, invited all the players, and created our characters. All of this was very easy. But then the troubles began. I was unable to figure out how to add player tokens to the map so they could see the map. I can add their tokens to the tabletop. But they cannot see the map. They only see their character in the Journal and a white Grid sheet on the tabletop. We can interact via video and voice chat, but they cannot see the map. I am sure I am missing something very straightforward. Thanks in advance. We still had a blast playing and can't wait until we can use the virtual tabletop.

Assuming you have set the tokens up with sight etc (do this before saving the token as the default), it could be that you haven't put the player ribbon on the right page . They would see a black, grid-less screen if it was to do with the dynamic lighting, a white one with a grid suggests they are seeing a blank page with no map etc.