This is just an unfortunate effect of downloading free software from a developer who can't afford to sign it!
Because RahiTuber has features that detect keystrokes and downloads from the internet (just to check for updated versions), that can get flagged in antivirus. All i can really do is give you my word that there's no malicious code.
You can either try to install it through the itch.io app, or you can try to exclude this website, or your download location, from your antivirus's detection.
Good luck!