IIRC the upgrade for the RAV4 for Carplay/Android Auto, they put a different microphone in the system. Just to be clear the upgrade will give you BOTH Android Auto and Apple Carplay. If you unplug the phone you'll have the standard built in system you have now.
The software is proprietary, so if it's on the internet at all it's not going to be easy to find and legally speaking you probably don't have rights to use it without paying for it.