First of all, the WPS feature does not work with the RPi3, yet. Also, the Digi+ is not yet fully compatible the RPi3 (https://www.hifiberry.com/2016/03/important-news-on-compatibility-with-the-raspberry-pi-3/).
However, you should automatically see the WiFi adapter recognized after the first boot of the system. You can also look into the Debug Info on the WiFi/LAN menu and see if there is a paragraph called „wlan0“, which should automatically appear with the RPi3 and our Jessie-based image (please use the Jessie-based image, if you do not already). Also, please try booting the system without any USB periphery, especially no WiFi-Stick.