If the Roku device you bought came with a voice remote, you can pair it to the TV. If it isn't a voice remote, it won't work with the TV. You'll need a physical remote to get your TV connected to your network. The cheapest Roku option is the Roku simple remote for TVs.
Roku TV Remote | Replacement Remote For Roku TV | Roku
Many universal remotes also support Roku TVs. You may be able to pick one up at a local store.
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