The SD needs to be plugged directly to a USB port on the computer per the gray print in this Apple article:
How to connect the Apple USB SuperDrive - Apple Support
No hubs or docking stations.
Also, if you need a USB-A to USB-C/Thunderbolt adapter, some very experienced users here have suggested the the three Apple adapters listed in the same article work far better than third-party models.
Please to not take the next comments as flippant or snotty because they are the most common causes of Superdrive issues:
1) Is the silver side up?
2) Is a disk in the drive? The SD will not show up on your desktop until you insert a valid disk.