I am started working in post quantum cryptography(lattice based cryptography) specifically in Password Authenticated Key Exchange (PAKE). I come across many PAKE key exchange scheme (like this one) that do not take in consideration the registration process and login process. These schemes simply assumes that two parties are sharing some secret password of low entropy and based on that they will generate common session key. So, my question regarding PAKE techniques are
What is the scope of PAKE schemes? Is Registration or Login process should not be considered while designing the PAKE key Exchange schemes?