As a school admin on IServ:

 

Step 1
Open the IServ administration. Then: Management - System - Single Sign-On.

 

Step 2
+ Add - Add OAuth Client

 

Step 3
Copy Client ID and Client Secret.

 

Step 4
Click on the "Restrictions" tab and activate Scopes there.

 

Step 5
Click on the "Application" tab and add "Redirect URLs" https://www.matheretter.de/sso/iserv (must match your server, so instead of www set, for example, he or nds or nrw). Then save.

 

Step 6
Create WebModule - Management - System - Navigation - Click + Add - and then fill out as shown in the screenshot - important! Replace he1234 with the username of your Edumaps admin account. Then save!

Example: https://www.edumaps.de/sso/iserv?id=he1234

Make sure to enter the correct Edumaps server here. So instead of "www" then "he", "nds", "nrw", etc.

 

Step 7
Switch to Matheretter. Log in with your admin account.

Go to "My Profile". There you will find a button "Create Single Sign-On". Click on it.

Now enter the IServ SSO data:

Done.