I know we responded by email, but for anyone else who might be wondering the same question:

How do I enter my company details on the order page?

You won't actually see fields for your business details on the initial checkout screen. Instead, you add this information right after your purchase. Once the order goes through, head over to your subscription management page at https://onestopsocial.com/billing. From there, you can update your profile with your company name and VAT/Tax ID, and generate an updated invoice that reflects all of your business details.