The book answer is kind of weird, and arguably changes the meaning of the sentence. I will add that I have only a vague idea of what active and passive voice mean, and can’t tell you whether you succeeded in using passive voice. I’m a native speaker, so I’ve never needed to know the names of these things.
In the active voice sentence: The sentence is talking to a group of people, each and every one of whom can buy a ticket at the counter.
In the book answer, the ‘By You’ significantly changes the meaning from the first sentence. Without that, it means that there is a counter for ticket sales. With the ‘By you’, it implies that a single person is able to buy tickets for a group at the counter. While you is used for both singular and plural, the context here implies it is singular. If it was addressed to a group, I'd expect 'Each of you' or 'all of you'.
Your answer fixes the problem with the book answer. Instead of ‘By you’, you used ‘By all of you’, which shows that you are still addressing the group. ‘By each of you’ might be a little clearer, but either is acceptable in conversation. You are also fine with your placement of the phrase. Both ‘at this counter’ and ‘by all of you’ are referring to bought, so they can go in either order.
The problem with both your answer and the book answer is that you pluralize tickets. If a person can buy one or more tickets, this is fine. The original sentence doesn't say whether or not you can buy multiple tickets, though.
A better answer would preserve the singular of ticket from the first sentence. "A ticket can be bought by each of you at this counter." Here, you need to use each, because each person is only buying a single ticket, as in the first sentence. If you used 'all' instead of 'each' in this sentence, it would mean the group as a whole could only buy one ticket.