More pictures in the linked paper; the captions mention that the position of the star is marked by the white star.

No, the white star is the measured location of the system's star, which has been subtracted from the image. The yellow-orange blob of ~16 pixels below and to the left of the star is the super-Jovian expolanet. There are more images in the source paper with different spectral filters, the caption on figure 8 describes the star:

https://i.imgur.com/KlgEVze.png

Take a look at this sequence:

https://i.imgur.com/STcNkIP.png

They started with the image at left, which represents a combination of both the planet and the star. Clearly, the star is so much brighter than the reflection of starlight off the planet that it blows out the whole image. But the star is pretty consistent, and definitely circular, so they could take a reference image and a rotated image and erase all the pixels that look like they expect the star to look. The difference between a normal star and the image they actually took is the planet-shaped hole left after subtracting one from the other.