"If we meet this evening, I will cook soup for you."
Translation:Bu akşam buluşursak, sana çorba pişiririm.
I think the answer to that is, because they made a mistake - specifically, when they started with this Turkish sentence they made the wrong translation to English, and then reversed the pair. I think the Turkish is what was intended, but doesn't correspond to the English.
I've added a long comment to this post with my current understanding of this, after reviewing the reference material. More clarification is needed.
no. Conditionals are really difficult to explain. But you need aorist here.
"buluşacaksam" in such a sentence could only be used in some rare cases. It is sort of hypothetical; for example my secretary arranges my schedule and I have no idea what she planned for me. So if one of the things she planned is that I meet you tonight, then I could say this. I hope it helps a bit. You don't really need to learn this part actually just stick to aorist :)
The grammatical notes do not address the correct pairing of tenses,
for various kinds of conditional, which is the essential point, and differs radically in Turkish and English. But there is an analysis on
the reference page
If you look at the pattern [aorist present] -> [present], that page gives two examples. These are
(1) Erken varırsanız, beklemelisiniz.
If you arrive early, you will have to wait.
(2) Erken varırsanız, beklersiniz.
If you were to arrive early [If you arrived early], you would have to wait.
(The English has an error on the reference page at this point.)
According to that model the sentence
Bu akşam buluşursak, sana çorba pişiririm
has the second form and means
If we met this evening I would make you soup.
while the sentence
Bu akşam buluşursak, sana çorba pişiriyorum
If I meet you tonight then I will cook you soup.
Now it's possible that the reference page is wrong, or that I am misreading it, but it is clear that according to all the information we have available, the Turkish and English do not correspond in this exercise, and that the grammatical notes offer no guidance on the essential points.
Another example from DuoLingo
Yakışıklı arkadaşı hızlıca buraya varsa herkes mutlu olacak.
If his handsome friend quickly arrives here, everyone will be happy.
(Should have been
If his handsome friend arrives here quickly, everyone will be happy.
but close enough.)
Thanks for this detailed information, but it's still difficult to get all these rules, and there is not enough support, but I am not mad of course as the course is free. But as I am repeating the course from the beginning it's easier and easier. I believe that this lesson and the ongoing lessons that comes after this one are difficult to comprehend on your own, but I will not quit. I will try to watch some Turkish series with my householders, as the Turkish series flooded the television here in Bosnia :)
For the "if" clause - I think the tips make a mistake labeling the "if" aorist as a "habitual" conditional. From every other resource, it is just a "real" conditional - something that is definitely or likely to happen, even if it only happens once.
For the "then" clause - Turkish uses the "then" aorist often in conditional phrases. Many of these result in the aorist serving some of its other roles besides repeated action.