The file is called .getxfer.8088.0.mega, i tried seaching it up on google but nothing came up.
That file is a temporary transfer file used to store partially downloaded files from Mega. https://mega.nz/
Apparently someone used your computer to download Payday 2 from an internet download site using Mega, which (until recently) could be done through your browser window, with no Mega software or Mega plugin needed. It quickly creates/reserves a placeholder file, the same size as the file you are downloading & slowly fills the placeholder on your hard drive with the file.
When the download is completed, it renames the file to whatever it was you were downloading. However... if you interrupt the transfer, the temp file remains so it can be picked up later. That is probably what that file is. An abandoned partial download. 🙂