Excel 2016 - textjoin emails from different rows into one cell depending on their group

(I have asked in the forum before about this, and got an answer. So I'm not sure if I should open a new thread for my question. But I modified it quite a bit...)

I wanted to join the emails of people if they are in a specific group. The data base is each person has one row in Sheet A. There are lots of people but not that many groups. For example, in group apple are 7 people. I want the email of these seven people in one cell on Sheet B. I need this to work with Office 2016, so the easiest solution that uses filter won't work, unfortunately. I marked the O365 solution green.

In group Banana are no people, but the formula I used, which is LOOKUP, fills Cell D5 with the names of group Apple.

First: Why
Second: How can I prevent it? The cell should stay empty. Is that possible?

Thank you!

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As there is nothing for banana, it is returning the value lower which, in this case, is apple.

Thank you. Solution in post #2.

Thanks for the rep.