The author remixed this model.
It's just a remix of the phone arm but it can fit on a Prusa Mini diagonally if you use zero loops (see slicer photo)
If you don't lower the loops to zero it won't slice. I haven't printed it (yet). It's the same thing just made shorter in tinkercad.
Yeah I know the middle is ugly but I didn't feel like messing with it in fusion so feel free to make a prettier one.