There are four primary files.  I recommend turning off Aux Cooling to avoid curling on the long rail.  It also helps to add a brim (mouse ears) and print the first layer at a slower speed (20mm/s).  Each of the four files will need to be rotated to its side.  Mine printed without supports.

The connector pieces are form fit and should be printed at 97% - 98%.

You will need to print 4 of the vertical beam connectors and 2 of the bottom connectors.