Aero bike (Atom 6) for climbing?

I am looking for a second hand bike, my budget is limited (750€ is what I can afford) and on top of that I am a short person living in Belgium where everyone riding a bike seems to be extremely tall so I am having a very hard time finding something decent in my size! I came across this bike from a belgian manufacturer, quality seems good (but if anyone has insights on the brand please enlighten me), he sells it for 600€, has rim brakes but honestly don’t care much, problem is that is described as a very stiff aero bike made for speed… but I don’t really care about going fast, I’m more into long rides with lots of climbs. I read many opinions stating that an aero bike is not good for climbing, but I wonder if this applies only to pros (couldn’t be more far from that) so I wouldn’t even notice. My issue is more about comfort since I plan on riding 90km and above? To add, bike is very light and equipped with full Ultegra.

Thank you all!