How can I fit this bottle holder to this bike?
That does not appear to be a attachment for mounting a bottle cage to a frame tube. The two holes in the mount appear to match the two holes in the upper plate of the cage, which orients the mount incorrectly for clamping a frame tube. My guess is that it's for mounting to handlebars - which have a standard diameter, unlike frame tubes.

mounts for frame tubes do exist. They typically use two adjustable straps of some kind to accommodate different size frame tubes. You want something with a beefy strap that can be tightened sufficiently to stop the cage rotating on the frame tube.