"Zombie fans" is one of those terms which has multiple meanings.
It can mean
1) People who love all things related to zombies
2) People who are fans of "The Walking Dead"
3) Fake followers on social media
The third is a straight translation from the Chinese term "僵尸粉", a term that originated from the internet, as one can see from what it means.
It is said that people even used zombie fans to "earn money" - they created fake accounts and followed a particular person, and after some time, starts to decrease that person's number of followers, and then sends a private message to that person to "ask" for payment so as to maintain the number of followers.
When it comes to money, people are indeed creative.
