All the options are greyed out, and unable to select a platform for some reason. Any ideas on why this may be?
It’s likely that your Unity Editor doesn’t have the proper build support module for the platform you wanna publish on.
Under the Installs tab in the Unity Hub, look for the editor install you’re using for your work in VRChat. Click the ‘Manage’ drop down and look for the ‘Add Modules’ option. If this option isn’t there, it’s likely because you’ve manually installed the editor and Unity wasn’t given the opportunity to properly install all the needed modules. To fix this, click the ‘Uninstall’ option in the ‘Manage’ drop down and reinstall the editor through the Unity Download Archive (https://unity.com/releases/editor/archive). This should automatically add the editor to Unity Hub, and the ‘Add Modules’ option should now be available.
In the Add Modules menu, you’ll need to download the build support module for the platform you aim to publish to. For Windows, add “Windows Build Support (Mono)”. For Quest, add “Android Build Support” (This should have a couple children modules attached to it). Lastly, if you’re using Linux, we’ll add “Linux Build Support (IL2CPP)”. Once you’ve selected the modules you wanna add, press the ‘Install’ button.