The credits were not a problem, but he still had to go through the process of graduation.
For example, the graduation thesis and graduation answer.
According to Professor Tang, Lu Zhou only had to prepare his thesis for this semester. He did not have to go to the classes if he did not want to.
Professor Tang said, "Honestly speaking, I was both surprised and pleased to hear you solve the twin prime number conjecture. I don't know much about number theory, but since you are so obviously talented in the field, why don't you try solving Polignac's conjecture? You already solved the K=1 scenario, so you just have to expand it into all natural numbers… But don't pick this as your graduation thesis topic as it might take you a long time."
Lu Zhou obviously would not pick a world-class conjecture for his graduation thesis.