Connecting to Kiwi 4 is a bit tricky for the first time.
Basically the reader can run in two different modes: Smartphone mode and Self-run mode. In order for the reader to work with RaceChrono, you’ll need to switch it to the Smartphone mode. Rather than having a physical switch, the manufacturer has opted to have you do the following:
1) Install the Kiwi OBD app
2) Open the Kiwi app, connect with it, and then configure everything, including vehicle details and passcodes
3) Only then you can switch the reader to Smartphone mode
After you’ve switched to the Smartphone mode, RaceChrono should be able to connect to from now on. If you have no use for the Self-run mode, I’d recommend buying the cheaper Kiwi 3 instead, as you do not need to configure it.