To be able to use VPN to access the GFZ network you have to activate VPN on the 'Passwords & Services' site on the intranet.

Go to asa.gfz.de.
Select "GFZ employees" and click Login.

In the new window, log in with your GFZ username and domain password.
Then enter the code from your 2-factor authentication device.

Click on "Download for Windows" to download the Cisco Secure Client.

Double click on the downloaded *.msi file and follow the instructions.
Administrator privileges are required for installation.

Open the Start menu and select the Cisco Secure Client.

Select 'asa.gfz.de' and click on 'Connect'.

Select "GFZ-Mitarbeiter" as the group.
In the new window, log in with your GFZ user name and domain password.

Enter the code from your 2-factor authentication device in the "Token" field.

Click on "Log in". The VPN connection is established.