The service must be selected in the menu below the Automatic Discovery switch. It should display the IP address of your computer. Tap this to select it and the IP should turn blue. Now you can tap Go to launch Griid.
IF THE IP DOES NOT TURN BLUE
There is a bug on iPhone 5 with Griid v1.14.6 where the menu layout is garbled, and this might prevent you from tapping the IP. The temporary solution is to unlock the rotation on your iPhone, turn the phone into landscape mode (where Griid is displayed correctly). You can now turn back to portrait mode or stay in landscape mode. Now you can tap the IP and it should turn blue.
IF THE IP IS BLUE BUT NOTHING HAPPENS
If nothing happens when you tap Go, try exiting the Griid app. Then double-tap the home button, press and hold the Griid icon until it starts wiggling and a red circle appears in the corner. Now restart Griid, switch Automatic Discovery off and on again. Try selecting the IP and tapping Go again. Bluetooth might be interfering with the connection, make sure to disable it on both the iPad and your laptop.
Make sure you have the following settings selecting in Live / Preferences / MIDI Sync (these are different than MIDI Connect, so it's worth double-checking):
Control Surface: Griid