Hi Michiel van der Velden,
the “.skp” file format needs Studio or Visualize to be read directly.
https://www.maxon.net/en-us/products/infosites/product-comparison/
Scroll down to Pipeline Integration.
A introduction to this is given here:
https://www.cineversity.com/vidplaylist/sketchup_to_cinema_4d/sketchup_to_cinema_4d_series_introduction
If you have no option to read this now, please as the artist working with Sketch Up to save it in an
Wavefront Object (obj)
Also possible
Collada (.dea)
FBX (.fbx)
3D Studio (.3ds)
perhaps with some limitation
VRML (.wrl)
STL (.stl)
others might work, but I like to ignore them here.
If in doubt, obj is a classic and most apps can read it.
https://help.sketchup.com/sv/article/3000153
If you have just one file, put it in a drop box and share the link (PM). For one time I can offer that.
All the best