When you’re done, tap Save, and you’ll see your rule presented with a toggle switch next to it. When you first turn it on, you’ll see a prompt to give SMS Auto Reply access to your notifications—it needs the permissions to detect when messages are coming in, and uses the Reply shortcut to send a response. After that, head back to SMS Auto Reply and try turning your rule on again. You’ll then be prompted to remove it from Android’s Battery Optimization—it’ll take you to the correct screen, but you’ll need to tap on Not Optimized at the top, head to All Apps, and select SMS Auto Reply to turn off optimization. Finally, back in the app, you’ll be prompted to allow SMS Auto Reply access to your cellular data, so it can send messages in the background. It’ll take you to the correct screen—just flip the switch next to Unrestricted Data Usage.