I have three bunnies in my living room and I’m pretty sure they don’t smell!
I use paper based pellets called back2nature. They’re not cheap, it’s about £12 for a 30 litre bag, but i use a thin layer and empty their two litter trays every other day and it lasts me about 6 weeks a bag, so actually it’s pretty good value over time.
Lots of people use non clumping pine pellets, but my spoiled brats refused to pee on them :,) they’re normally pretty cheap and are absorbent and non-smelly.
I would recommend emptying litter boxes every other day and wiping out, then giving a proper rinse once a week.
Air fresheners and candles aren’t good for buns unfortunately- they have sensitive lungs and it can harm their respiratory systems. A good alternative is something like rosemary, mint or lavender in a window box, which have strong scents and are also safe if your bun decides to nibble them!
Finally, to make the urine itself smell less you can spay and neuter bunnies (essential if they’ll be living together anyway). Some people also use a dash of Apple cider vinegar with the mother (the mother bit is important) in their drinking water.
Also, I know you didn’t ask about this, but if you’re getting a second bunny it’s really worth reading the bonding forum to make sure you know how to help the buns safely become friends! It can be a long and stressful process, but will be worth it in the end! 