In an interview with Beyond the Trailer, Snyder confirmed that his version of Justice League exists outside the current DCEU timeline. With that he doesn’t have to take into account Man of Steel from 2013 and Batman v Superman from 2016.
“Frankly, the DC Cinematic Universe is like a tree that thrives and grows in amazing ways,” said Snyder. “For me, Justice League is its own way. It is separate from the DC cinematic universe and is going its own way and I think it is a good thing.”
After years of campaigning, the film that Snyder had in mind was finally made. The film should be available on HBO Max in 2021 and could be a four-hour movie or even a TV-like series consisting of several episodes.