You asked about both an Express and a Stick. Those are not the same thing, so either there's a confusion of terminology, or you're talking about two different devices.
The Express model 3900 (the suffix is the distribution channel) comes with an IR remote. In the US, that model was discontinued and replaced with a newer one in 2019. I don't know if a Voice Remote will work with the 3900. I suspect not, based on the Accessories page on Roku's Website, which lists models supported by the various accessories.
If you also have a Stick, the Voice Remote will work with it.
DBDukes
Roku Community Streaming Expert
Note: I am not a Roku employee.
If this post solves your problem please help others find this answer and click "Accept as Solution."
