Your thought that the ridges (I don't know the correct term either) will cause a problem is correct. So will the window locks on the side and the crank handles that I assume you have at the bottom (not shown).

You "might" be able to mount the shade to the "ceiling" portion in front of the window but it will take some precise measuring by someone familiar with the dimensions of the shade headrail.

Not sure where you are located, but I would reach out to a local window treatment dealer in your town (instead of trying to buy them online).

Good luck.

Thank you so much for your feedback. I was thinking of hanging three separate ones from the ceiling, but as you said, I’d need to do some precise measuring. Also, I hadn’t taken the handles into consideration. 😫

Actually, I just looked and the handles wouldn’t be a problem!

Since we cannot really see the detail of the window "ridges" I suggest you call in a blind supply company to come and measure and inform you of what can be done. I would prefer to see the blinds installed inside the window frame, not above.