It's complex to explain, but it's not a technical glitch or a configuration issue; it's part of how marketing works.
Basically, the more your game is shown, the more impressions it gets.
The more people who receive those impressions click on your product, the higher the CTR.
On its own and without context, the CTR doesn't give you much useful information; you need to analyze it in the context of your promotion.
For example A, you advertise your game on several pages, and you have a low CTR. This means that the advertising isn't effective because your product reaches many people, but it doesn't capture their interest.
For example B, you don't advertise at all, and your game only receives visits from a specific Itch tag, and you have a high CTR. This means that your product is interesting to people searching for that tag.
Note that example A may have a low CTR, but you may still have more downloads/sales than example B.
Therefore, to take advantage of CTR, you also need to analyze your marketing strategy.