I tried that as well, but then it says iGo cannot be found. Therefore I thought the SD card should stay in the radio.
To summarize what I did
1. Copy the appradio plus files on an SD card and put it in the radio
2. Install AppRadio plus. When the installation is complete, turn off radio and remove SD card.
3. Boot radio, click on Igo
4. "iGo cannot be found".