I think what they’re saying is, the amount of ordinary matter in a galaxy, by new more accurate measurements, is enough to explain the rotation of that galaxy, without the need for dark matter.
But I don’t see in the article how this addresses the movement of galaxies relative to one another, and the expansion of the universe as a whole.
If their calculations are right, then the presence of dark matter is not required to explain the internal motion of galaxies. This says nothing about the way they move wrt each other. It just weakens the argument for dark matter a bit.
But see below the article posted by moonman62. It seems that previously dark matter was well accepted as contributing to galaxy rotation so the jury is still out. This is just one result. It needs to be confirmed.