@Jiyuu , Same, I'm confused too, still waiting for anyone to explain clearly in comments lol. My understanding is that perhaps MC is saying he needs to find a labyrinth with 100 floors and get to the 100th floor, not necessarily the current labyrinth they are in because it only has 80 floors, he were aiming for the 100th floor in this labyrinth only to find out that there are only 80 floors unfortunately, so he wants to continue his journey to find the 100-floors labyrinth, which maybe they can find in other continents.
"Akira, you were aiming for a level 100 area of this labyrinth?" "Yeah." probably means that MC initially thought this labyrinth has a level 100 floor and was aiming for that floor based on the Commander Saran's advice, only to find out that it only has 80 floors, so he has to test his luck to find a level 100 floor in other labyrinths that may or may not have 100 floors.