All Mustangs 2015 year or newer are push to starts. The main antenna for the push to start is located in the center console. You'll run into this symptom if you unplug that antenna and don't return it before finishing installation.
2016 Ford vehicles's need a USB media hub swap to get Apple CarPlay and Android Auto working. Here is the install for an F-150. F-HUB-SML F-HUB-R3 F-HUB
If you've purchased the Ford Mustang 4" to 8" Sync 3 upgrade and watched our installation video you may see that there are two small cables that are mentioned and is missing from your kit. We are sorry for the confusion, but we've improved our kit to ...
When going from 4" to 8", you will have a new switch on your bezel for Driving Modes. No Mustangs coming from a 4" should have that feature, and you do not gain it with this upgrade. It is possible to get it, but we are not aware of the specifics.