Unfortunately, Android OS is not able to support the open standards for address books (CardDAV) and calendars (CalDAV) ex works. Therefore, an additional program must be installed that synchronizes the Android address books with the address books of the CAU cloud. For this purpose, we recommend the tool DAVx⁵. You can download this program for a fee from the Google Play Store.

Alternatively, you can install another app store F-Droid for open-source applications like DAVx⁵. There, open-source programs are provided free of charge, and the project is financed by donations. Please note that programs from alternative app stores like the F-Droid store are not subject to the review processes of the Google Play Store.

If you have installed DAVx⁵ from the Play Store, you can go right to Setting up synchronization springen.

• Set up open source appstore F-Droid
• Installing DAVx⁵ for synchronization
• Setting up synchronization with DAVx⁵ as CardDAV client

Set up open source appstore F-Droid

To install the alternative app store F-Droid, load the app store page at https://f-droid.org on your Android device using a browser of your choice. From there, select DOWNLOAD F-DROID to download the application as an akp file. Android will warn you that apk files can be potentially harmful, confirm the download. After that open the downloaded application, if not already done Android will ask you to allow your browser as a source to install applications. Confirm this by enabling the Allow from this source switch in the settings. Go back to Installation and start it by clicking the Install button. Open F-Droid directly with the OPEN button. At the first start F-Droid will need some time to load the package lists.

Installing DAVx⁵ for synchronization

To install DAVx⁵ from the F-Droid Store, open the F-Droid and open the search box using the magnifying glass. Now enter dav as a search term and download DAVx⁵ by tapping on the arrow next to the DAVx⁵ entry. Once the download is complete, a button labeled INSTALL will appear in place of the arrow. If not already done, Android will ask you to allow F-Droid as a source to install applications. Confirm this by enabling the Allow from this source button in the settings. Go back to F-Droid. Start the installation by clicking the Install button.

Setting up synchronization with DAVx⁵ as CardDAV client

When DAVx⁵ is started for the first time, it will go through a short setup process where some settings are made and the required permissions are obtained from the system. Follow the setup steps until you get to the permissions. Here, specify the permissions to access contacts and/or calendars, depending on what you want to synchronize. If you want the synchronization to run automatically in the background, you can also allow the application to run in the background afterwards. Otherwise, you will always have to start the application manually for synchronization.

You will now get to the list of synchronization profiles, which is still empty at the first start. With the +-button you can create a new synchronization profile. Choose from the options Log in with URL and Username and enter the following data.

• Base URL: cloud.rz.uni-kiel.de
• Username: Your username in the CAU Cloud, e.g. suabc123
• Password: Your CAU Cloud password. If you use 2-factor authentication, you have to generate an app password

Confirm the credentials with the REGISTER button and select the item Groups are categories of contacts in the following dialog in the contact group method. This will attach a sortable label to the contacts in the android contacts app according to their CAU Cloud groups. Select CREATE ACCOUNT to complete the configuration. After a few seconds, you should see your address books in the contacts application.