If you register a device on a specific site on the Airfob Space, you cannot register the same device on an another site. If the device registration fails, check whether it is registered on an another site or not.

https://supremainc.com/en/platform/suprema-mobile-access.asp
1. Check Site ID
Sign-in, access Settings, and access Site. Check the Site ID.
2. Biostar Integration with Airfob
Access Biostar, access mobile access card, and integrate site.
Integration of Mobile Access Card, integrate site, and register device.
When complete, the device will be registered on Airfob Space.
3. Check Device Registration on Airfob Space
Sign-in Airfob Space and choose the site you have integrated with.
Check if the devices registered on Biostar show up correctly on Airfob Space.
Note:
The site on Airfob Space and the site integrated on Biostar must be identical to see the same devices show like above.
If devices do not appear on the list, check if the site ID you have registered on Biostar for integration with Airfob Space is the same site ID of Airfob Space.