The error is shown when Microsoft NTFS by Tuxera can not write to the preferences file.
Please try the following:
1. Uninstall Microsoft NTFS for Mac by Tuxera
2. Open macOS Terminal and remove any remaining Preference list by inputting:
sudo rm -f "/Library/Preferences/com.tuxera.NTFS.plist"
3. After that, please try to install again. This will create new preference file and should let you input your product key normally.
If the problem is not solved, you can contact our support team at email@example.com