Probably best to contact you local Archicad distributor.
I feel your anguish - I'm still waiting for the AUS version which is about 2 weeks away.
Seems like the 'download' link on the Spanish site doesn't do anything.
And if you go through the menu on the right (the 3 bars) and go to support and downloads, you will end up at the link you provided and it shows version 25.
Someone just hasn't updated the web sit properly.
But on the link you provided you can just change it to 26 in the URL or choose 26 in the version option.
Sorry, I don't actually read Spanish.
Yes that was a link just for the update 3010.
The initial installation can be found here ... https://graphisoft.com/downloads/archicad/install/AC26/SPA
I thought that link was wrong too.
It shows 25 when you hover over it but does seem to download 26 OK.