Make sure you are using the Safari browser since it is the only one that Apple allows to access the camera.
Make sure your device is updated with iOS version 13.0.0 or above.
Allow access to the website when prompted for camera permission. If you are not prompted for camera permission, make sure you enable your browser to have permission to access the camera.
Go to Settings on your device
Scroll down and open Safari tab
Ensure Camera & Microphone are set to Allow
Make sure you are using the latest Chrome browser version. We advise to set Chrome as your default browser through your phone's settings as it tends to work better than the other preinstalled browsers.
Also make sure you enable your browser to have permission to access the camera and allow access to the website when prompted for camera permission.
Make sure to have Google Play Services for AR installed on your Android device.
Make sure to upload high contrast images with multiple details in the shot.
When uploading an image file to be used as an image target, our system checks for the contrast and detail complexity of the uploaded image. This validates that AR-enabled cameras will be able to detect the image.
Here is an example for a good image: