There are a couple of reasons your company information may not appear in the email footer.
Sending Test Emails
When sending a test email using the Send Test button in the drag & drop builder, the footer will be present but the merge fields will not populate.
Sending To One Contact
The footer will not populate for one-off emails sent when using the basic editor (text-based).
So when does the footer populate?
Your company information and footer will always appear when using the drag & drop editor, when sending to more than one person using the basic editor, AND when you have an email set up to send as an automation (like in response to a form being filled out, campaigns, etc).
To edit your company info, go to Account Settings > Account > Company.
To see what the company information in your footer will look like, send an email to two or more contacts in your database (including yourself).
More on Footers —
The basic editor footer cannot be changed and is in a standard format. The information included is pulled from the company information set in account settings.
Note: The footer only populates if sent to two or more people OR if the email send is part of an automation. A one-off basic email is not considered marketing communication.
Here's what the footer in a text-based email looks like --
Drag & Drop Editor
The drag & drop editor provides many different footer layouts to choose from while building your email. This footer will populate with every email send.
Here's an example of what the footer would look like in a newsletter-style email --