Please make sure you have accepted all moto updates on your phone. There may be a series of updates, so please double check that you phone is fully updated.
Once fully updated, please try register with the QR code again.
Can you please share the build number of your moto edge+. It can be found in the Android Settings app:
Settings -> About phone -> Build number
For example: S3SH32.12-41
Also, please make sure you are not using the version of the Lenovo Universal Device Client (UDC) from the Google Play Store.
See this post from the forum for more details about correct UDC versions: