The license acquisition process is completely free. The price of the license itself depends on what is the purpose of given license. But since this is a community effort with no profit, it can be acquired for free
Obviously you need to contact them so they can notice you. There is no 'correct way' to do it, but what we can recommend from our experience is to use the contact form on their motorsport website (https://www.skoda-motorsport.com/en/contact-us/) - they will get back to you with further instructions you'll have to follow in order to acquire the non-commercial license.