Old client renewal - how to do the map

I’m totally new to UE and I’m trying to get some ideas/directions on how to implement this. I have an old client for an online game I made years ago and I’d like to renew it while learning UE. The client contains a 9x9 tiled 2d map. When the player moves, a new set of tiles data is received from the server and redrawn over the previous. While normally only 1 line of tiles could be sent (player moves 1 tile per move action), some locations can “teleport” the player, so the entire 9x9 map is sent on every move, even if normally only 1 side of the map contains new data and the remaining 8x9 is just the old data “scrolled” in the correct direction.
I’d like to redo the map view, but using 3d objects instead of tiles. The map needs to stay on the server (it’s big and dynamic and don’t want players to decompile and see it - there is an exploration component in the game), but the client can contain the “3d tiles” used to build the 9x9 overhead map. Tiles can represent a mountain, forest, road, etc.
Any idea on how to proceed? I’d like to understand what direction to take, what to study/investigate, etc. Just some suggestions to get me in the right direction would be useful.

Now that UE4 is free I don’t think it’ll take much for players to look at your map.

Off the top of my head (very quickly) I wouldn’t send tiles myself but implement some sort of fog of war system so you can only see what you’re allowed to. Tile objects can be replicated so they stay synced wit the server’s vision.