Hello,
Thank you for contacting us and sorry for any inconvenience that might have been caused due to that.
To change the permission for each role head over to WordPress Dashboard > Rank Math > Role Manager and select the appropriate permissions for each role on your website.
The setting that allows to show the On-Page Schema is called “On-Page Schema Settings”

Hope this helps solve your issue.
Don’t hesitate to get in touch if you require any further assistance.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.