Could not add MiTag MiLi to Find My

I could not add the MiTag MiLi to Find My. Here is the steps taken:

Step 1. First time setup, everything went okay until it stuck at the Finishing setup, at which then I exit the Find My.

Step 2. The next time I tried setting up, it showed the error Unknown Error after choosing the Emoji.

Step 3. I tried factory reseting many times as well as tried adding on other iphones but it did not work either.

Please advice.