To make the release synchronization work, you need to set up some permissions in Azure DevOps.
First of all select the project corresponding to the one in StoriesOnBoard.
Then go to "Project settings" in the left bottom corner, select "Project configuration" and "Security" from the "..." menu next to the root project.
After that, you can add a user group or a single user to the permission settings.
Then you need to allow "Create child nodes", "Edit this node" and save your changes.
Note: for users who are part of the project admin group, these settings are not necessary.
Now your team should be able to keep DevOps iterations in sync with StoriesOnBoard releases.