They are allowed to be a part of the ACC's lower tier bowl line up - but I'm not sure about number, etc...

But because you were referencing "auto-bid" I think you were inferring them receiving an ACC contract slot to a NY6 game which they don't technically have.

ND's "contract" is for the side opposite an ACC team in the Orange Bowl. That slot is contracted to the highest ranked (by the committee) of the 2nd highest available place B1G or SEC team or ND...with a caveat that all 3 of those entities will be in that bowl at least twice in the next 12 year cycle.

This criteria doesn't exist in years where the Orange is a semi-final game. Which means at the end of the 2015, 2018, 2021 & 2024 seasons they can't go to it as part of that contract. That leaves 9 seasons for the 3 entities (B1G/SEC/ND) to be represented at least 2 times each.

This at least 2 times each may make it so that in some years it may not be the higher ranked being pulled into the game...but it's intent unless forced otherwise is to take the higher ranked team of the 3 possible....

So that isn't an ACC slot - that is a setup to play against an ACC team in the Orange Bowl.

http://en.wikipedia.org/wiki/College_Football_Playoff#Bowl_selections

Also here is a snippet about the ND / ACC agreement

Although the Notre Dame football program is not a member of the ACC, it has an agreement to play five ACC schools per season in football starting this season. This is in return for access to the non-College Football Playoff ACC bowl line-up.

http://en.wikipedia.org/wiki/2014_Atlantic_Coast_Conference_football_season

And here

* Notre Dame sponsors football as an independent. Although Notre Dame has a commitment to play five games per year against ACC football teams, it does not participate in the ACC football standings and thus is not eligible for the ACC football championship. Notre Dame does, however, have access to the ACC's bowl lineup aside from the Orange Bowl, to which it has its own arrangement for access.

http://en.wikipedia.org/wiki/Atlantic_Coast_Conference#Men.27s_sponsored_sports_by_school