Hatchbox by default creates a personal account for you, but that account is only for one user (you) and you cannot invite other users.

To invite other users, create a new team account. All new accounts in Hatchbox are team accounts. Once you have a Team account, you can invite other users to join your team through the Hatchbox UI. 

If you would like to move a cluster from your personal account to a team account, you can do so by going into the cluster settings to the "Transfer Ownership" section. Enter the same email you used for your personal account to transfer the cluster settings to your new account. You will receive an email asking you to accept and you will see a drop down to select the new team account to complete the transfer.