Given the limited enrolment capacity of Hong Kong universities, mainland universities will remain the first choice for the majority of mainland students.

I find that "given" is ambiguous, do you think so ?

3 given
Given is used when indicating a possible situation in which someone has the opportunity or ability to do something. For example, given the chance means `if I had the chance'.
Write down the sort of thing you would like to do, given the opportunity.
Given patience, successful breeding of this species can be achieved.

4 given
If you say given that something is the case, you mean taking that fact into account.
Usually, I am sensible with money, as I have to be, given that I don't earn that much.
= considering
5 given
If you say given something, you mean taking that thing into account.
Given the uncertainty over Leigh's future I was left with little other choice.


Could it has the 3rd explanation or the 4th and 5th ?

That is, does the sentence mean "If the capacity is limited..." or "Considering the capacity is limited.."

Is it ambiguous?Emotion: smile
It's the fourth and fifth meaning (these are the same thing)- taking into acount that that the universities have a limited enrolment capacity.

It's not ambiguous.