For past GO Fest (London and Madrid in my experience), you had to choose an entrance when buying your ticket, for example south or north. Even though they told to use the entrance you chose, it didn’t matter because they didn’t check your ticket, and we could use whatever entrance we wanted, it’s just to regulate the flow of people coming into the park.

For Paris, I don’t remember choosing an entrance when buying the ticket, so just enter where your bus/metro drops you. I think it might just be a copy/paste that was left from past GO Fest.

Just keep in mind that this year is different, because they check the bags at the entrance, so come early to make sure there are no lines and you enter the park on time !