I checked the do it yourself sticky here and found someone posted a DIY cabin air filter replacement the for a 2010 XC60, I'm just wondering if the location of the air filter is the same on the 2015.5 XC60?
Just tug your carpeting back and have a look. it's real easy to check. I would be surprised if they relocated the filter location. ...but Volvo is full of surprises sometimes. I did the how-to in the sticky. If it's in the same spot, it is super easy compared to some other models.