If the Roku Premiere 4620 as is listed on your account here is what you are talking about, the remote that is sold with it is an infrared (IR) remote that does not need to be, and cannot be, paired to the Roku, so it does not have a pair button. It works by direct line of sight so make sure your Roku is placed in a visible location with its front facing into the room and that nothing is in the way to block the signal from the remote. It should just work as long as it has good batteries installed.
To check whether an IR remote itself is working, you can point the remote at a digital camera (a phone will do) and press some buttons on the remote. If the remote is working you will be able to see flashes on your camera's view screen.
Roku Community Streaming Expert I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well. If this post solves your problem please help others find this answer by clicking "Accept as Solution.".
Streaming Stick 4K+ 3821 | Streaming Stick+ 3810 | TCL Roku TV 43S245/C107X