The author remixed this model.
I needed the spool to be on the Right Side of the printer, so I remixed the one from @Jswinfo_123089 since it was a really clever and non-destructive way of mounting it to the side without drilling any holes.
It works by tightening the clamps with the bolts that already come with the printer (2 M3 x 50mm fasteners)
You also need 2 nuts.
Download the clamps from the original model here: Qidi X-Max3 Side Mount Spool Holder by Jswinfo | Download free STL model | Printables.com