Where you keep your crock when it's fermenting is really up to you. But the temperature will effect the speed of the fermenting process.
If you keep the crock in a warmer place, it will ferment faster. However, if it is colder, the fermenting will slow down. If it is too cold, it can slow down the process to the point of virtually stopping. And on the opposite end, if it's too hot it could speed it up too much and end up rotting before you know it!
An average room temperature is best. We like to keep our crocks on the floor or counter top in our kitchen. This way we can keep an eye on it and listen for that "popping" sound which means it's fermenting away!
If you have a root cellar or basement with a concrete slab, you can put your crock directly on the cold floor once it is finished fermenting. The cold in the concrete will transfer to the stone crock to provide a steady cool temperature for storage. This is the time when you want the cold to stop your fermenting process.
The taste of your final product will be different based on the speed and length of fermenting. So experiment! That's the fun part of fermenting, the smallest variable can completely change the results!