In the movie clip 18 sec you can see the passage way , behind the red painted hull part. They will probably install a walk way on graetings to make walking easier,

08:16 (5 seconds ago)
Hi Henning...thanks for the link....Interesting stuff.
(Didn't see a tunnel as such though, as mentioned by Denis.)
Loved the two guys with their pocket tape measures, checking the gap was parallel!
The launch was quite impressive too...well-made short videos there. Cheers.

Yes they have.
Pls see here : https://www.wagenborg.com/news/construction-easymax-2-in-progress-with-transport-aft-ship

Denis.
They only hire crew members who run the 100 meters in 8 seconds.

That'd be quite a run to the lifeboat in case of emergency! I wonder if there's a tunnel inside the ship connecting front & aft so one won't wander across the whole ship in rough weather.