I divided the model into 4 major parts to avoid support structures using Microsoft 3D Builder.
See my make ( https://www.thingiverse.com/make:351007 )
Please note that there is a mistake in the original STL-File. Some hubs of the track rollers have no contact to the base an can't be printed correctly. See red arrows.
TigerAce1945 alredy fixed these errors in his files.
Many thanks to the designer TigerAce1945