If demand exceeds supply.
I've never had issues getting into the European ACS when they've said its number is limited each year.
It sells out every season, I know people who have missed out in the past
The issue this time is, for 2 seasons prior we got to the final, the semi would have hardly any tickets returned from uefa, so lots will have got 3,4 or 5 credits not 6, but the ACS required 6 to enter...
But with only getting to the quarters last year, the number on 4 will be a lot higher than the previous seasons numbers on 6 and the number of seats in the ACS will remain the same
Other cups are the same, more will qualify than dont, but the reality is people dont enter the ACS as much for those cups so likely credit will drop to only needing 1 or whatever
I'd still say the chance of ACS for CL is like 80%+