Thanks for reaching out here in Roku Community.
Let us help you get connected with the Roku mobile app. Before you start using the Roku mobile app, check that your mobile device and your Roku device are on the same wireless network. If you are unable to get your Roku device to connect to the same network, you'll need the actual remote to connect your Roku TV to your wireless network.
When the Roku mobile app launches it will discover any Roku devices on your network. Select the Roku device/TV you wish to control using your Roku mobile app. You will then be taken to the home screen where you will be able to control your Roku device.
If your Roku device does not appear on the discovery screen, learn why the Roku mobile app may not be able to find your Roku device.
See more details, on this related support page: How to use the Roku mobile app to control your Roku device without a remote.
Keep us posted on how it goes.