Issue while Going Live including domain purchase

Greetings,
I am trying to go live and purchase a domain from ALLProWebTools.com

When I go live it says this "The domain name: stxconsulting.co is available for purchase at $1.00 / month.
Do you want to purchase it now from AllProWebTools? (If you have already purchased it, please check the spelling to make sure you entered it correctly)"

As I click "Purchase Domain" it encounters an error

"Unable to charge credit card Visa **** **** **** ****. [curl] 60: SSL certificate problem, verify that the CA cert is OK. Details: error:14090086:SSL routines:ssl3_get_server_certificate:certificate verify failed [url] https://www.namesilo.com/internal/api/b ... ansactions"

please guide me about the cause of the error. Is APWT trying to charge for domain from card? If so, why and how much it will charge? Isn't it monthly basis?
Also my bank is not showing any charge attempts.
Is there any issue in back end or something else?

It is quite urgent. I would appreciate if you could check thoroughly and guide me.

Regards,
Trannum

Please verify that you want to purchase: stxconsulting.co or stxconsulting.com. When you reply, we will purchase for you and process your go live immediately.

Hi Dave,
stxconsulting.com is unavailable

so will go for stxconsulting.co

Your website is now live here: https://www.stxconsulting.co/

Your new login to the website is https://www.stxconsulting.co/logmein