A question that comes up time and time again on this forum is whether there is a manual for the ARC app. Beyond the Quick Start Guides, the answer is - nothing official that is produced by Scalextric.
However, I have started a thread on the the new SlotRacer Online site which uses race simulations to introduce the various features of the app: https://slotracer.online/community/showthread.php?tid=181
Instead of putting together what would be a huge and unwieldy user manual, I hope the practical guide will get people using the app for racing straight away and will encourage you all to explore the app and use your own imagination to develop race formats and simulations that work best for you and your racing pals.
The guide is based on ARC Pro, but should be also be useful for people using ARC One and ARC Air. I do plan to include some two-car analogue race formats to the thread in the future.