Lux Trail bottle size

Hello everyone! This is my first post here and also my first Canyon. This precious Lux Trail CF 8. I want to install two bottles but I have a problem with the size of them. I bought an S size and two 650 ml don't fit. I want to buy fuel mud cup water bottles from Canyon but before buying them I wanted to know if anybody had that same problem and wich size should I get. Thanks in advance for the help!!