What file?
It’s a printer, without a connection to a computer, which generates a bitcoin address and prints it: private key and public key.
To receive you scan the public key. When you eventually want to send you scan the private key.
So you can receive without ever exposing the private key, except on a piece of paper and in the air gapped printer.
At least that’s what I deduce, I don’t have one and haven’t seen a description.