diff --git a/docs/app-config-guide.md b/docs/app-config-guide.md
index fb719b3..40d7341 100644
--- a/docs/app-config-guide.md
+++ b/docs/app-config-guide.md
@@ -18,7 +18,7 @@ Check [this approach](https://git.autonomic.zone/ruangrupa/login.lumbung.space).
 
 #### How do I integrate with Keycloak SSO?
 
-Use [this plugin](https://github.com/pulsejet/nextcloud-oidc-login). You can use [this trick](https://janikvonrotz.ch/2020/10/20/openid-connect-with-nextcloud-and-keycloak/) (see "Cryptic Usernames" work-around) to get proper usernames.
+Use [this plugin](https://github.com/pulsejet/nextcloud-oidc-login). Unlike the plugin it's forked from, there is no configuration UI, so you'll need to edit `/var/www/html/config/config.php`:
 
 ```
   'oidc_login_client_id' => 'nextcloud',
@@ -37,6 +37,10 @@ Use [this plugin](https://github.com/pulsejet/nextcloud-oidc-login). You can use
   'oidc_create_groups' => true,
 ```
 
+You can use [this trick](https://janikvonrotz.ch/2020/10/20/openid-connect-with-nextcloud-and-keycloak/) (see "Cryptic Usernames" work-around) to get proper usernames.
+
+You might also need the following "Why is my synchronisation.." change if you see an error `'redirect_uri' is invalid`.
+
 #### Why is my synchronisation client freezing on the "grant access" step?
 
 Please see [this ticket](https://git.autonomic.zone/coop-cloud/nextcloud/issues/5).