You baked a normalized heightmap, which means 0: lowest point of the model, 1: heighest point of the model. With default actor scale (100, 100, 100) Unreal expects terrains to be in 512m range. So, the z scale of the terrain actor should be max_texture_height (cm) / 512.
Alternatively, you can bake the heightmap with a scale of 512m (51 200 cm).
X, Y scale: with default actor scale (100, 100, 100) landscape vertex density is 1m. So a heightmap resolution of 1009x1009 produces a 1km wide terrain. Get the longest dimension of the model (X or Y) and that’s how wide the terrain should be. You can get higher or lower vertex density by changing the x, y scale of the landscape actor.