exported xpi themes are corrupt

whenever i export a theme as a .XPI file after making one on https://color.firefox.com/ and i try to install it into Firefox it gives me the error "This add- could not be installed because it appears to be corrupt." and i cant fix it

I think you need to upload that XPI to AMO in order to get signed first. The error message indicates that the file isn't signed, which makes sense (somehow) because Firefox Color doesn't sign add-ons.