I'd suggest you download the free app called Boop Light Detector.
Run that first and see what it indicates for light over the items you want to
use Seeing AI on.
It gives off beeps and the faster and higher pitched, the brighter the light.
Then, as Donna suggested, make sure in the menu, settings
When you downloaded the appdid you allow the app to have access to the camera?
Have you gone into settings & turned off the light? When installed the light on
the camera is automatically set to on. If you have turned off the light you
will have to make sure the room you are in is brightly lit.