Messenger Plus 4 installer not even starting

Hi. So I’m trying to install Messenger Plus! 4 on my computer to use with WLM 8.5 but the program doesn’t start. It gives the error “Windows cannot access the specified device, path, or file. You may not have the appropriate permission to access the item.”. I have tried basically everything including compatibility mode. I am running Windows 10 20H2. Please help.