Originally Posted by
Richard Bell1 lists the S9 as compatible, with a note that says it requires the OTG adapter. The S8 does not require the adapter.
As soon as I saw that, I wouldn't buy the camera. Either it's a USB source or a USB consumer, it can't be both. And a camera
should require an OTG adapter (or they should supply an OTG cable with it).
Just make sure that your S9 USB isn't set to power only or power the connected device only. It should be set to MTP. (And the way Oreo and Pie have been going, check that each time you plug the camera in. The setting doesn't always "stick".)