Open the Site Access app and click setup in the menu. Once setup is open, click add new door. Follow the prompts and then scan QR code on the door controller. After the door has been scanned follow the prompts to enter the door's settings (can see the wiring diagram from here). Continue to follow the prompts.
After you click done, click yes to associate a camera to the door. Click add vigil camera and proceed to scan the QR code on the camera. Follow the prompts and review the settings for the doors. At the end of the setup you will have the option to take a picture of the setup and email it.

Watch the video below for an example:

Door and Camera Association