You need 2x per roller axis. They are meant to be press-fit. If you put them on the outermost of each axis you are able to use spools up to Prusament spools (are my widest).
Hint: The sleeves are for the bigger-spool-inserts :) In the comments I got the information that you need to scale it down to 70% in diameter to use the sleevees with the smaller ones. (Not tested by myself)
Improvements:
Print:
Please see my other models used for my drybox based on a IKEA Samla box: https://www.printables.com/@Mike_88377/collections/1315141
The author remixed this model.
Additional TPU sleeves for the spool roller.