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-potsdam.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 Any Connect 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 AnyConnect Secure Mobility Client.

Select 'asa.gfz-potsdam.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.