On Android you also need to install the DavX app to sync calendars and addressbooks. Connect to https://fairkom.net/nextcloud/remote.php/dav/
iOS/macOS users connect to https://fairkom.net/nextcloud/remote.php/dav/principals/users/yourusername/ - you find the correct link on the left bottom of the calendar tab in the webview of nextcloud. There are Problems reported with the synchronisation of caldav and carddav on macOS 10.15.5. Either try this or try to install thunderbird with lightning calendar add-on.
If you want to sync an existing calendar and addressbook which is local on your device, you need to export and import them to the new calendar and addressbook.
nextcloud file management and syncing plus several useful apps
circles to manage groups
Some features are only available with fairapps basic or fairapps pro.
With fairapps-basic or fairapps-pro you can manage memberships in circles. Members need be also activated with the circles app, so they can confirm their membership.
For organisations, we usually set up a special organisation-admin account, who is the owner of a main organisation folder. This user shares the main folder with the group (but is not itself part of the group to avoid circular share issues). An independent main folder owner is to prevent troubles, if a founding user would leave the organisation. An admin could transfer the ownership of a folder to another user, though: sudo -u www-data php occ files:transfer-ownership --path=“name of folder” usernamefrom usernameto
Alternatively, the groupfolder app may be an option which we are currently testing.