What version of the main plugin are you using?
Version 2.0.52
What version of the Custom fields addon?
Version 2.0.6
What value do you have in the “custom fields” settings of the individual product?
One Field Text Label: Full Name (and checked as a required field)
One Field Text Label: E-mail (and checked as a required field)
Which radio options are checked in that section?
Both is required