I solved the problem. No need no texture manually.
What I did was import as .dae and when it was in my viewport on the terrain I looked at model's object attributes folder. I saw an option to change the asset file folder, so I changed the folder to the asset foldof the model as an .obj. I clicked generate model and a new .obj model had appeared with all textures. It was however extremely large, so I need to down-scale it.