This pops up when i run the installer

Can you try uninstalling and reinstalling the latest version? You can download the latest version here: Download FxSound - Boost Your Sound On Windows

this type of pop-up happens when a .msi file of same software is deleted from the C:\Windows\Installer folder. like i don’t even understand that why make a copy of installer when .msi installer has already installed the program. A simple reinstallation should fix that for you.