Sadly the sales pitch for the Honda Connect system does not match the reality, Andruec’s theory about different versions of Mirrorlink probably explains why.
I would also like to install the App Goggle maps for navigation purposes via my mobile WIFI unit or tethering from my mobile.
AFAIK you can only download apps from the Honda App Centre, and there was very little there last time I looked, certainly nothing as useful as Google Maps (Honda are unlikely to make a navigation app freely available, they would prefer to sell you a car with Navigation installed).
There is a way to get a map display without faffing with Mirrorlink or any other app, although unfortunately it’s not very useful. Set your phone up as a mobile hotspot, then connect the car to it via WiFi. Then use the browser on the car unit to open Google maps. You’ll be using your mobile’s data allowance and positioning system. But you’ll probably find it very clunky and slow, and in any case the screen will blank when you drive away: HONDA deliberately prevent anything resembling video from displaying whilst the car is moving.
It’s much easier to forget about integrating your phone with Connect, just get a phone mount and use it for stand-alone navigation.