First of all, you need to make sure that your collection is ready to be scanned. After you open the app and you log in with your CraftAR account, go to Settings —> Active Collection —> Change and check if the collection Status is Ready (if not, tap on it to synchronize).
Once you have done this, if you still do not find anything after scanning, this might be because the quality of the reference image you are trying to scan is not good enough. You can read our tips to improve the image quality in the following link:
Hope it helps,
Catchoom Support Team