I found out that this is sadly limited to the Administrator only – but changing one line in class-submissions.php file in the plugin folder helps.
Is: if (!current_user_can(‘administrator’))
Should be: (!current_user_can(‘edit_posts’))
Still, this would be overwritten with the next update, so it would be great to find a way to give the Editor a full access to the ER Forms functionality simply using the plugin settings!