"You would like our books."
Translation:Libros nostros velitis.
'You (plural) like our books' would use an indicative. Maybe libri nostri vobis placent or libros nostros amatis.
Libros nostros vultis would be 'You want our books' (vultis being indicative instead of subjunctive velitis).
I don't think they are trying to say 'you would like' as in 'you would enjoy (if you read them)' but more as a way of saying 'you would want (if you could have them)'. If they are talking about enjoyment, I don't know why they are using a form of volo, velle (to want, to wish).
I honestly don't remember all that much about the subjunctive anymore, but there are a lot of different uses that change the meaning.
I'm pretty sure, though I stand to be corrected, that the English, "You would like our books" that we are suppose to translate into Latin, is in the subjunctive in English. I am also pretty suer that in this course we have not yet learned the subjunctive in Latin. Therefor, I am suggesting that the English be changed to the simple present indicative by removing the "would". Again, I am no expert, I stand to be corrected.
Translating would like is introduced in the notes for Market. Here are the notes on it (I have seen some other sentence discussions were the politeness part is disputed by users):
I would like
In English we use the phrase would like when requesting something politely (in a shop, restaurant etc.). In Latin, however, we need a special verb form to express this. You would use velim in such situation.
(Velim is the subjunctive of velle, volo, to want. For now, you don't need to remember this information.)