No, you need not enter your Full Name, Email ID or Phone number to search for your contact details for Job/Shift signup.
You can search for your contact details by entering partial details of First Name, Last Name, Email ID or Phone number.
Note: If you search with your full Name, Email ID or Phone number then the search lists only your contact information for you to Signup and Check-In. If you search for your contact info with partial data then the search brings up all the names which have related data as in your search.
e.g.: if you search for a Volunteer "Anthony James" with his full name then you see only his name appear in the search result
But if you search by entering "Anthony" then you see a list of Anthony available in your Org as Anthony James, Noah Anthony, Mason Anthony, Jacob Anthony etc.,