I am not sure how you wanted to validate the website but I added the URL of your website to the licenses page and using the purchase key on the WordPress dashboard I successfully validated your installation. I followed the article below:
I suggest that you check our knowledgebase articles, especially the setup section to get started:
Also check the Pro related videos there.
And finally, to get used to the Header/Footer builders which use the flexbox display I suggest you look into the videos below: