Go to https://cat.eduroam.de.
Click on the blue button in the middle of the site.
Then select the College on the left.
On the next page you can select your operating system, the page tries to propose the correct system automatically. Download the program by clicking on the corresponding button.
After the download a dialog opens automatically, confirm the next two questions with "Continue".
Enter user name and password here. The user name is composed of the account name (E.g. abc123) and the realm of College @hnee.de (E.g. firstname.lastname@example.org)
To complete the installation, you must enter the password of your Mac OS user.
eduroam should now connect.