What you need first
Two things: an account on the Infralytiqs console, and a ClickHouse server the platform can reach. If you do not have the second one yet, a Docker container is fine for evaluation and takes about a minute — step 3 covers it, and the ClickHouse guide covers doing it properly.
You do not need a credit card, a sales call or a trial licence. You also do not need to decide your event schema up front, because custom dimensions are map columns you can add to at any time.