There was a solution here, but it got removed by the solution writer. So I just wanted to provide some helpful words and a video to fill the void.
First, check out the solution for this same achievement on the Xbox One Ezio Collection version of AC Revelations:
If the video there doesn't help you, here is another I found.
This video shows the whole Lost Archive DLC. I linked it at the timestamp for Memory Five (26:53-31:21) but you can watch the rest if you need to
video credit Zevik on YouTube