The city of Neel had a total of five gates on different heights of the mountain. Not all the vampires were eligible to pass through all the gates. The gate located at the bottom of the mountain was the general one and every person was eligible to pass through it. It had no restrictions.
But the second gate located one thousand meters above the ground was special and only a select few were able to pass through it. Elena and Tomoe were already eligible to pass through this gate as any adventurer with B rank or higher could freely go past it.
As for the third gate, anyone who wanted to go past it needed special permission from the city hall. The only people who were an exception to this rule were vampire nobles of marquis rank or higher and S rank powerhouses. So Elena and Tomoe could also go past this gate.