makerworld puts all raw files behind the "stl" label - so there are scad scripts and 3mf files. The 3mf there containing only geometry and are not a slicer project. - Maybe you like to address and report this https://makerworld.com/en/my/support/tickets
It is a press fit, but as I used other existing models to get the dimension it is strange that it doesn't fit - what diameter is your post? You find a bigger version with 3.75 as raw file.