Volunteers without an account on Track it Forward are able to sign up for events, however, they will not be able to keep track of their hours unless they have an account created. To allow volunteers without accounts to sign up for events, you will need to enable this feature for each specific event individually:

Go to Events

Click on the specific event

Click on Edit

Under the question "Require Track it Forward account in order to RSVP?", select No (by default it selects yes)

Then click on Save

When the volunteer goes to sign up for the event, they will have the option to select "Sign up without an account". 

Then they can enter their name, email, phone number, and an optional message to the organizer.