Hi, the option is only available to supervised devices that have been enrolled during the set up, Ensure through the server in put section of organisation is preferences you've pasted the link to add new device. If you've enrolled the iPads via the QR option after set up it won't work. You'll need to wipe the iPads and start again for Meraki full features to be enabled.
https://documentation.meraki.com/SM/Device_Enrollment/Enrolling_and_Supervising_iOS_Devices_using_Apple_Configurator_2.0_or_Later
Hope this helps.