You can only tether from your main profile.
You need to enable app updates on secondary profiles before booting into them. Its a security feature for you to toggle on and off.
You can decide whether to download apps in your main profile and then sympathetically install them in any of your tertiary profiles, or you can enable updates and downloads in specific profiles.
You can also disable any apps you've installed in any of your profiles without uninstalling them. You decide what's best for you.
axs