I fixed your link (Underscore rather than hyphen).

the article is certainly interesting, but a lot is left unsaid, or anadressed.

For instance the report states:- "The calculated density is close to Earth's, suggesting that the planet's composition is similarly rocky."

But this is a misunderstanding of planetary density. The planet is observed to be about 1.8 times the radius of earth and about 5 times its mass, so the nominal density is 85% of the earth's. The error is small, and those input values are uncertain to some degree, so the answer *might* be true that the planet's composition is similar to earth, until you factor in self-gravitation and compression.

The material at the core of a rocky planet is compressed by the weight of what's on the outsuide and it gets denser. This is not a trivial process: the Earth has an actual mean density of around 5.5 g/cc, while the materials of which it is made, if found in a small uncompressed asteroid, would have a density of only ~3.9.

So the mean density of the bulk materials that constitute the Earth has been increased by a factor of 1.4 by the compression due to gravity.

For the Exoplanet, there is MORE gravity and MORE mass stacked up, so the compression effect should be even larger. The exoplanet will have a surface gravity 1.5 times that of Earth, so we should expect 50% MORE compression. We see, in fact, 14% LESS compression than on earth. It has a compressed density of ~4.7 g.cc

So, to a first approximation, this exoplanet is made of bulk materials LIGHTER than the earth.

How light?

If we simply take the same ratio of compressed to uncompressed density as the Earth, we get an uncompressed density of 3.34, but if we allow for the stronger gravity, we see an uncompressed density of only 2.75. (it isn't a linear relationship)

(Mars has a compressed density of about 3.9 and an uncompressed density of ~3.4)

This is MUCH less dense than Earth, and suggests a significant amount of water, or ice, on/in a rocky core and crust - or possibly a thick gaseous atmosphere around a metallic core.

For all the hype, this still isn't anything like the Earth, or anything else in our parochial Solar system...