Hi Luke,
To clarify the situation, I'd like to confirm the following information:
1. Which Office 365 subscription do you sign up?
2. Do you mean you do not receive the email with the User ID after you sign up Office 365?
If this is the case, please make sure the Business email address matches the one you mentioned. Can you newly sign up an Office 365 trial plan to see whether you can receive the email with the User ID using the same email address?
3. Regarding " I received a purchase order with product key but no ID", can you provide us with the purchase order for investigation?
4. Regarding the "temporary ID", do you mean you do not get the notification email, including User Name and Temporary Password as an admin after newly creating a user?
If there is any misunderstanding on your situation, please let us know with more detailed description.
Best regards,
Mills Fan