Using the numeric version of any command in the package CharacteristicClasses needs version 1.3 or higher of Bertini to be installed. Download and installation of Bertini are explained at the Bertini homepage.
Bertini should be installed in a directory in the user's PATH. As an alternative you can tell the package how to find Bertini. Usually, when the package is installed, a file called init-CharacteristicClasses.m2 is created automatically in the user's application directory. See also the option Configuration under newPackage. In the file init-CharacteristicClasses.m2, replace "" in the line "pathToBertini" => "" by the path to Bertini in quotation marks, for example "pathToBertini" => "/usr/local/BertiniLinux64_v1.3.1/". The / at the end is important. Windows users should use the path relative to the cygwin directory, for example "/usr/local/BertiniWindows32_v1.3.1/" if Bertini is installed under pathToTheCygwinDirectory\cygwin\usr\local\BertiniWindows32_v1.3.1 .
To check whether Bertini is working properly with the functions in the package CharacteristicClasses, use bertiniCheck.