I don’t think this is a Mac problem. On my Mac I was able to open and work with your file without crashing and export both of your pieces as .stl and load them into Cura for printing just fine. I generally do not experience much crashing of SketchUp or Layout on Mac.
This might be a problem with your specific installation or a conflicting extension, is SketchUp loaded into the applications folder, not running off the desktop?
You might be running into the tiny geometry issue when using solid tools on such small geometry.
SktechUp has a lower tolerance of about .001", edges smaller than that such as are created in tiny radius curves cause errors and prevent faces from forming, it could also be causing crashing if you are running out of ram in calculating the number of edges created in a complex solid operation, although the edge count for this model is pretty modest at around 50k.
General best practice for 3D printing is to model at 100 or 1000x scale. I model in M and treat them as MM, many others do the same. With this practice I never have issues making any type of complex geometry. .STL is a unit-less format, so the actual units used to model is not recorded in the file, what matters is the unit set in the import process into your slicer. I leave my SketchUP model in meters, export as-is without any scaling, and have set Cura (my slicer) to read all .stl files as MM so there is no scaling on either end, things just appear in the slicer at the correct size, this is a common workflow.
The 2021 release of SketchUp introduced an unfortunate Bug which causes the Export Selection function to fail, in any file format. There is no error window, it appears to export, but no file is created. You cannot 3D export a selection only until this is fixed with a new release, no telling when that will be but the SketchUp team is painfully aware of the problem. For now you can copy paste to a new file and export, or download the STL export extension from the SketchUp team which will restore the export selection function through the file menu.