You are asked to require a site visitor to enter First name and Last name...

In Permissions, check "Require first and last name for user registrations"

In Account settings, under "Who can register accounts'?" select "Visitors, but full name is required"

In Account settings, go to Manage fields and add fields for First name and Last name. Set them to "required."

Create a block type with fields for First name and Last name, set them to "required" and add the block to the/user/register page.