Hi Fuzineli,
The problem is resolved by checking the language and format settings in the ossuser.
Please login to the server as the ossuser (if you haven't login yet try the default password Changeme_123) after that considering you are using Windows go to Control Panel>Region and Language Settings.
Under this menu select the language to be English(United States) and check the format settings, the decimal should be "." and the digit separator should be ",". After doing these changes please try again.
The problem is the U2000 can only operate in Simplified Chinese or English language which is preventing the backup from being made. Also when the U2000 tries to check the available disk space it encounters an error in the available space since the operating system reports a number with decimal point (for example 800.000.000,00 instead of 800,000,000.00 assuming an 800 GB HDD)