superdrive not working on iMacM1

Hard to say without being there but here are things that cause the SD to not work

1) The drive is upside down. Silver side goes up.

2) The drive is connected through a hub or dock. It must be directly to a USB-A, USB-C, or Thunderbolt 3 or 4 port on the computer

3) The wrong cable adapter is used. The three listed in this Apple article are the most reliable:

How to connect the Apple USB SuperDrive - Apple Support

are you aware that a superdrive will only appear in DU or on the desktop once you've inserted a disc.

also, with a superdrive, the desired actions need to be set for what type of disc is inserted. go into System Settings > CDs & DVDs, and choose your actions.