Once again I have to mention, that the platform buttons on the itch page WILL NOT magically turn a Windows build into one for Linux or MacOS.
Please switch the target platform in your Build settings (possibly need to install the Unity module in the hub first), and make another one. (Note: while the Windows build target will be put into a new folder, the Linux one will be right in the folder you select, so please make an empty forlder for it.)