Android Auto not working, says need to install app / non supported app

You won't believe this but other users report (documented here https://support.google.com/androidauto/forum/AAAA6SY52nIKxb3deoJU_Y/?hl=en) that you need Hangouts installed (and not disabled) for Android Auto to work with messenger and SMS type apps like Textra, WhatsApp or Facebook Messenger.

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