Yes, USB-C to USB-A (3.1/blue colored) cable might be preferable option, but still and in order to make sure that USB-C to USB-C cable (why not?) of your choice found your device it is slightly better, IMO, to use Jumpdrive (just another script), execute sudo fdisk -l (or something else) to check if your Librem 5 already recognized from your computer side and when asked/introduced to:
just take out your Librem 5 battery and put it back in. Your install procedure should continue from there as well, without disconnecting/reconnecting any data (5Gbps or 10Gbps) USB cable again, the one that is already connected to your computer (perhaps USB-C to USB-C data one, not sure as didn’t try this myself).