Would you post a screenshot of the topo map? Importing as a static mesh is not going to function correctly with foliage and other landscape tools, I think. It’s much easier to generate a grayscale heightmap and import that to create a landscape from it quickly. It requires a bit of editing of the black-to-white heightmap image in a program such as Photoshop or Inkscape, such as blurring and smoothing / sharpening, but it’s easier than trying to recreate the exact terrain of a 3D map with the sculpting tools. There’s also a plugin called TerraForm that is for importing 3D map data to Unreal Engine, and it might have a few pointers for importing a CAD topo in the web site tutorial about that plugin / application. Different parts of the tutorial are accessible by links to the topics, like a table of contents link list, and here’s a link to it:
Otherwise, I’m not sure if there’s a way to transform a 3D CAD survey map to a UE landscape within UE. Try looking up the release notes of 4.25.3 and 4.25.4 for CAD under Landscape / Terrain, or in the docs.