Hi Lukas - in order to qualify them for the project outside of having a Wikipedia page, we have to perform the same process as Wikipedia would do related to obtaining them a Wikipedia page. They must be proven to have done something "notable" - i.e., something famous, unique, historical, etc. that is proven and supportable through a significant number of sources that can be validated. The biography for these individuals must be fairly significant, as it is the only central source that we can rely upon to reflect their specific accomplishments, demonstrate the sources utilized, and prove that they have the requirements for being acknowledged as "Notable". Most profiles have people who have done something "notable" in their lifetime, but not everyone would qualify as "Notable" or qualify for a Wikipedia page, so we do have to screen these carefully. Independent and unique sources are key as we cannot simply acknowledge that these individuals are Notable based on our own opinion, but that they qualify based on multiple sources that acknowledge what they are notable for.
Hope that helps.