I mean, if that's where your usb_install_pc.py is then it did work. But ehh, long as you got it. :D As for your other issue, not sure. My card is ExFAT and I have had no issues loading anything. 6.2 / with the latest Atmosphere.
cd into the folder where usb_install_pc.py is, then:
python3 usb_install_pc.py /where ever the folder is containing your nsp, hit enter.
Note: It can't link directly to the nsp, just the folder the nsp is in.