There are some extensions that can drop the buildings down to the terrain level, but they will only get you so far. In this case your topo information is pretty rough, in actuality the streets and each of the lots would be level or closer to level. Putting flat buildings onto a curved surface requires a judgment call in each case to get a result that feels close to reality. You will likely need to adjust each building manually no matter how you approach this, @pbacot s is a good method, it’s not that many buildings.
Here I use an extension to drop all buildings to touch the topo, but as you see there is still adjustment needed individually.