You need good ventilation up high. Ammonia is lighter than air and will rise to the top. It needs a way to get out of the coop that is over their heads when they sleep. You may also need to clean out the poop. It may be building up too thick. Ammonia is created from their poop.
Most coops smell because they are too wet. In rainy weather that can be hard to overcome. You are likely to get a whiff of wet chicken or the poop in there can start to smell a bit, but if the coop is basically dry, it should not be overpowering. A lot of moisture in the air can cause some smell.
If your coop is too wet, the smell can get really strong. That can also be unhealthy for them. If your coop is wet, you need to figure out how to get it dry and keep it dry. That may mean fixing leaks, putting something over windows or vents to stop rain from blowing in, or if it is on the ground level, stop water from running in there. If your coop is really well ventilated a bit of rain blowng in through a vent is not a big deal, but a lot of rain coming in where the bedding becomes wet is a huge deal.
Instead of treating a symptom, look for the cause, probably either poop buildup or too much moisture. A droppings board is a great idea. Keeping it pretty dry and ventilated is essential.
Then there is the other side. If you feel it has to smell as clean and clear as the inside of your house, good luck with that. That is not a normal natural smell around chickens. I sure can't help you achieve that.