It could be one of 3 things:
1. Wrong size rotors
2. The e-brake shoes are not seated properly and preventing the rotor from fitting over them.
3. The e-brake is out of adjustment.
Here's some links that may help:
Replacing rotor:
https://www.youtube.com/watch?v=C9HIaHaoZSo
Adjusting E-brake:
https://www.pelicanparts.com/techarticles/Boxster_Tech/55-BRAKES-Replacing_Brake_Discs/55-BRAKES-Replacing_Brake_Discs.htm