Tunnelblick manages OpenVPN – in fact, that's Tunnelblick's purpose. Tunnelblick uses OpenVPN's "management" option to tell OpenVPN that it will be managed by Tunnelblick. If an OpenVPN configuration file includes the "management" option specifying that some other program should manage OpenVPN, there would be a conflict. So to be used by Tunnelblick, an OpenVPN configuration file cannot include its own "management" option.
To use your configuration file with Tunnelblick, you will need to edit the file to remove the line that contains "management". You can do that in any plain-text editor (such as TextEdit).
You might want to consult with whoever gave you the file and ask them why it was included; there may be other options in the file that cause problems, too.