Answer:
Saber
Step-by-step explanation:
"Saber" means "know" in English.
Translating your queestion to english is: "fans do not ________ how to get to the new stadium."
Filling in the blanks you would assume what makes the most sense, which is the word "know".
So in spanish it would be los aficionados no saber cómo llegar al estadio nuevo.
Hope this helped!
De nada!