Whenever the website doesn't mention details, it should be taken to mean "whichever way feels comfortable and better to you", in any exercise, not just the chakra spinning. If the direction was important, it would mention it. For example, I always spin them counterclockwise. If I try to spin them clockwise, it feels as if I'm being drained of energy. But I've seen people who say clockwise feels better for them.
Focus on the spin, not the direction. Worrying about direction of spin will only distract you, just focus on spinning them and let them spin whichever way feels most natural.
You can rotate the chakras in any direction convenient for you. I feel the same effect and result after rotating the chakra to the left (clockwise), or to the right (counterclockwise).