As an interrogative pronoun, "que" is what and "qui" is who. Therefore, in the example given, it can only be "what do they like".

Qu'aiment-ils? -- What do they like (que --> qu')Qui aiment-ils? -- Whom do they like.

As I said, the answer given by kwiziq seems wrong, because it said LOVE.  

The issue here is why LOVE was the answer.

Qu'aiment-ils is LIKE, Correct? 

When it comes to things, to "love" or to "like" is almost synonymous: I love sugar vs. I like sugar. The former is, maybe, a bit more intense than the latter. And it is similar in French. Aimer can be translated as to love or to like, depending on context.

I was expecting something more "indepth" and specific than the obvious "what aimer can be defined as."  I am well aware of the flexible use of this verb. 

Kwiziq had an incorrect/lame answer. I'm trying to help but obviously that's not what this forum seems to be about. 

Have a nice day.

I can't know what you are aware of or not, Darren. I try to help when I can. I am not part of the kwiziq team and simply volunteer my time. Sorry if you expected a better answer, I hope you'll get one.

Let’s just say my expectations for a precise answer haven’t been met, but the Kwiziq app sure knew what was “wrong” but apparently without any specific support behind it.  

Not exactly a great experience. 

Have you looked at this lesson?

Aimer = to love, like something / someone

Have you looked at this:

https://www.lawlessfrench.com/grammar/aimer-lesson/

And did it help you?