When setting up ConnectSense HomeKit capable devices, HomeKit requires certain permission to allow a user to add a device to their home. The error will look like this in the ConnectSense App:
Note: Screenshots are from iOS 14, this could vary slightly based on the iOS version you are using.
To resolve this, contact the primary account holder of the home. The primary Account holder will have to grant permissions to the user trying to add the device. To do this, follow Apple's instructions found here - https://support.apple.com/en-us/HT208709.
Once permissions have been granted, the user will have the ability to add the device to the home.