Cannot contact theme creator

Hello, I am trying to contact the author of a theme that I have recently bought, through his website, where he offers support for the theme, but when I try to register, I am getting an error saying that you don’t have made any purchases.
Any help?
Thank you

P.S.“the author of the theme is pixel grapes.”

If you have troubles with their website you can simply post a comment about this on the item’s comments section or contact them in a P.M here: