Yes, any edge drivers, custom or stock, must be on your hub before the devices added.
Presumably all of the stock drivers will be added to customers hubs before the phase 2 transition begins, but they aren’t there yet.
The stock drivers that you can get now are in the beta channel. So you have to subscribe to that channel and then select the edge Drivers that you want.
Note that some of the fingerprints in some of the smart things written edge drivers are commented out right now. So it’s not enough to see the fingerprint, you have to make sure there’s not a /* before it as well.
To get a custom edge Driver, download it to your hub, you follow a link that the author gives you, subscribe to the channel, select the drivers that you want, and then wait. It can take as much as 12 hours before they are download it to your hub
For the details on how to see which drivers are already on your hub, see the community FAQ. That will also tell you how to find community-written custom edge Drivers.
FAQ: I have no idea what Edge is. Is that a new developer tool? (2022)
Remember that during phase 1, which is where we are now, you can only get an edge Driver for a device already on your account by deleting and re-adding the device.