3D PRINT SETTINGS:
All STL files are all already oriented properly.
No need for supports, or brim.

The hangers print on their side and don't need support, even for the overhanging part.

For the hangers, you can pick between 2 lengths: 245 or 280mm.
I find that the longer the more convenient, but go with whatever fits on your print bed.

The bottom plate of the rack will appear "full", this is not a mistake.
You need to turn it into a "mesh" by selecting an infill pattern of your choice, and setting the top and bottom layers to 0.
On the example on the pictures, I used a 20% honeycomb infill.

Layer height: 0.2mm/layer
Wall line count: 3
Top layers: 0 (to cancel top face)
Bottom layers: 0 (to cancel bottom face)
Infill: 15 to 20% (honeycomb on the pictures)
Build adhesion type: None
Supports: None