In that case I suggest you post a picture of the UVs in unreal. Open up the static mesh viewer and hit the 'display Uv's' button. This is to make sure that unreal is importing the UVs correctly.
To check if it's related to the meshes, you could assign the material to an unreal cube or sphere and check if it works there. Don't know how those materials are set up, but often times the UV tiling is parameterised, so it can be overwritten in material instances.
you don't have any materials applied to your mesh. All the meshes just have 'lambert1' applied to them (see image). You need to setup the materials in Unreal. here's some info: https://docs.unrealengine.com/4.26/en-US/RenderingAndGraphics/Materials/IntroductionToMaterials/
What are your computer specs? Sometimes unreal will downsize textures when memory is scarce, sometimes quite a lot. Not usually to that extent, but I imagine it could happen with a lower spec computer, or with a graphics card that isn't quite compatible. UE eats up a LOT of RAM too.