I am from Pakistan, I want to know about eVisa. I don't have a Schengen Permit. How do I get an eVisa for turkey?
The visa requirements are detailed here. The reason the e-Visa website asks about a Schengen, US, or UK visa or residence permit is that it's not possible for you to get an e-Visa without one.
Instead, you are supposed to apply for a regular visa. As far as I can tell, it's not necessarily more expensive but it means you have to go through a slower process and provide more information in advance.