Created Samstag 17 Juli 2021
Login as administrator. Browse to Profile menu - Site Administration - Athentication Sources.
Click Add Authentication Source.
Settings for Nextcloud
Setup a OAuth2 client in Nextcloud.
Authentication Type: OAuth2
Authentication Name: Nextcloud_<Provider Name> -> E.g. Nextcloud_Hetzner
OAuth2 Provider: Nextcloud
Client ID (Key): Copy'n paste from Nextcloud Settings - Administration - Sercurity - OAuth 2.0 clients Client Identifier field
Client Secret: Copy'n paste from Nextcloud Settings - Administration - Sercurity - OAuth 2.0 clients Secret field
Enable Use Custom URLs instead of Default URLs.
Replace <own-server> in the fields Authorize URL, Token URL and Profile URL with <Nextcloud URL> e.g. <Service name FQDN>