I got a warning on this game, too. I tried deleting the folder (the game sadly isn't for me. It looks well put together, I just don't like the characters much) but the .tmp file threw up a red flag. It refused to be deleted, even though I'm the administrator. I finally had to have it scanned for viruses, and that's when I got the 'Password Stealer" warning and the file was moved to quarantine.
There is a string of scams going around atm through posts claiming "Updated Versions". All VNs will not post links to updates and you should only download from the direct links on the main itch page. Please give your computer a thorough virus scan if you've inadvertently downloaded a scam version. This scam is ongoing across the platform and we are deleting them when they appear but please be aware.