Currently the model of the Redgum build plate shows two wiper pad mounts instead of the auxiliary mount cover. We will need a new render and to update this prior to release.
Could you try to play with tessellation settings in FreeCAD: Preferences->PartDesign->Shape View. To see if it woud reduce the filesize.
Also apparently @karrad was post-processing the file in blender, so make sure the origin of this STL file is lower-left corner, on the build surface.
Ideally we shouldn't post-process the STL file coming out from FreeCAD, because I think scaling factor might've been introduced by blender.
I did a fusion of all the parts, then created a mesh with 1.0mm Surface deviation and 30o Angular deviation and exported it to binary STL.
(2nd way described here: https://www.freecadweb.org/wiki/Export_to_STL_or_OBJ
The resulting file is 0.5MB