What for is this payment?

Good day, I’ve just signed up. Before registration, I asked chat about payment, whether I would be charged immediately or I could register for free and change to the free plan and won’t be charged. It said registration is for free. After registration, I got a request for 9.06$ from my account, but there was not enough money for the payment. Why did you try to charge me even if I didn’t use anything yet? How can I change to the starter and now and miss the payment for the pro plan now. If it’s not possible I ask you to delete my account and delete from the schedule for payment on 5th of may. Thank you in advance for you help.