Nope, it was labeled correctly. :) It is but a baby and will look like most of the images of a 'Golden Barrel' cactus down the road (eventually). Planto

Well that explains why I could not find anything similar enough before. I believe it may be an echinocereus viridiflorus then.

Hm, I see that most Echinopsis oxygona cacti on Google have very short (or virtually no) thorns, but perhaps this is a different subspecies or cultivar, anyways it definitely is an Echinopsis. Thank you very much :)

Well, it´s dead. But some plants in the same container seem to be doing OK, which have obviously had the same conditions. We can only really guess at the reason, could even be some obscure infection, or no real reason at all, but like other folks say, your soil does look a bit suspect. There are as many favourite soil mixes as there are growers, and I have now firmly settled on a well-draining gritty mix with a good proportion of limestone for my desert cacti, with just a little organic material. I totally avoid soggy peat, which means any commercial ´cactus mix´, as they are invariably full of peat or even worse - ´forest product´- read sawdust. A gritty mix in unglazed terra cotta pots will set you up. Err on the dry side rather than overwater - it is quite difficult to kill a cactus through underwatering. They are succulents - they will store water when it rains heavily, then be well able to survive drought conditions for weeks or even months.