First of all i want to add that no one can confirm that this is a real Pinball.
We have some sugestions here but after some time investigating this i cant confirm its clearly a pinball, cause u cant play or activate it.
(ofcourse for the moment and who knows if we can find the way to play with this pinball in future).
Anyway here you have your answer, for get the way to this pinball is so easy, i add 2 screenshots from depot of oramond
Go downstairs and follow the next image
As i told u before i went there for some hours and i didnt find anything, the only "especial stuff" is that u can find an NPC in the top of this structure where u can make a task for oramond quest.
I hope i helped you,