There are many instances where there is an individual who purchases the tickets or items for multiple people. In the case this is your scenario, the administrator would have to activate a setting whereby this is enabled so that information is auto populated and collected per individual ticket attendee (in this case: first name, last name and email).
e.g., if a team lead ends up purchasing 10 tickets for a group of people from a university. Normally the person buying it would just input their information in and credit card information. However, in the case you want to collect information in regards to who exactly is a part of the 10 tickets, you can activate this setting in the "Purchase Items" section and the below is a setting:
Once this setting is turned on, by default when navigating to the "Custom Fields" section, there are two tabs, one for the order and then another for the actual "ticket". Note: by default moving forward, the fields first name, last name, and email will display as required fields: