In each pair, the first phrase is about having accomplished (or not) something in the past:
Before arthritis got to his back, he had been able to change his own oil
Before he got his GED, he hadn't been able to get anything better than work as a laborer
The second phrase in each pair is about opportunity, most typically that was missed:
He could have gotten her autograph if he'd had the courage to walk up and say "hi".
He couldn't have eaten the last piece of cake, he was away at school all day.
This is a common misunderstanding. Your sentence mentions an action. That action seems to be in the past. The statement uses the present tense. Why?
Some verbs express action. Other verbs express state of being*. The verb "to have" expresses a state of being.
1) I saw the film.
2) I have seen the film.
3) I had seen the film.
In 1), the only verb is a past-tense action verb.
in 2), there are two verb words which form a single verb phrase. The "have" is a present-tense state-of-being verb. The "seen" is a verb without any tense but with the perfect aspect. This form does not express the action of the verb "to see". It expresses the result of that action.
I have seen the film. I possess a result of the action.
In 3), the "had" is a past-tense state-of-being verb.
The structure of 3) is rarely used on its own. Often, it's used to suggest that one thing is even further in the past than another:
4) I had seen the film when I read the book.
The action of "to read" is in the past. At the time of the action of "to read", my state of being included the result of the action of "to see". This suggests that that action of "to see" happened before the action of "to read".
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* As far as I can tell, we use the phrase "state of being" because the word "condition" would be confusing. Verbs like "to be" and "to have" express a condition in the sense of "the way things are", rather than the sense of "something required for something else". We use the word "condition" in the second sense when discussing subordinate clauses, so we use "state of being" when discussing what a verb can express.
Best Answer
The first sentence is in the simple present; it indicates that you have that opportunity now, which means that you will, if you seize the opportunity, be holding the conference in the future.
The second sentence is in the present perfect; it indicates that the opportunity took place at some point in the past, meaning that the conference also took place in the past.
When using the present perfect, there is a clear grammatical implication that the action spoken of has been completed. The opportunity is not completed until the conference has taken place.