When your Veative order was placed, an email address for the admin contact should have been collected along with other contact information.  The account invitation would have been sent to that address and should look something like this: 

Check with the person who placed the order, confirm the email address, and check that account (including the Junk, Spam, or Bulk Mail folder) for an email from notifications@veative.com. 

If you can't find the email, please open a support ticket using the button above.