Payment No Show So filling out form to fix - what is PGP Signature? : DarkMatterMarket | Torhoo darknet markets

My payment to my order on Dark Matter market never showed.
When i log in to check order today, there's a post by Black Mask saying they may have some problems with deposits not showing.

I checked the order and it's canceled for no payment. I most definately sent from my wallet on Tails. A wallet that's not mine has the xmr.

I checked Black Masks post again and it says, "ADDED: if your order was rejected and you can't follow steps above, go to this page and do manual verification. Pay attention that you need PGP Signature, which of course you verified and saved before transfer money as you was told to to do."

I'm doing that but kind of stuck on question 2...PGP Signature.

What is this PGP Signature? On Dark Matter, I am set up for 2FA with my pgp public key. When i set it up in Kleopatra in Tails, it created a ID for Encrypt and an ID for Certify, Sign. Does this have something to do with that?