I appreciate that you want to defend buyer rights
That is not what I did. I am telling you that you that someone stealing your game is an unlikely explanation.
People pirating games from Itch do not do so by sharing account data or download links to Itch. You need to assume software pirates stupid enough to do so and more, a lot of people dumb enough to download directly from Itch via a pirated link or log in with shared account data.
if this were one genuine customer struggling to download
And you know that it is not so, because.... ? While 89 times is high, but I would manage to do that manually, if I am frustrated that it does not work. Would take about 3 minutes, spread out over an evening. Could even be the Itch App itself, trying to download the file over a faulty line.