I replied to slitherine (pl_support@slitherine.co.uk) and contacted Plimus customer support... but actually it seems like a weird and irregular error as it pops to an XML "Access Denied" page when I try to download, not to a well formatted error page.
It is really disturbing to buy a downloadable game and not being able to play as soon as you buy. That is extremely frustrating, as today I can stay at home all morning (that's why I got the game today) but I'm not really sure to have that much time to play soon...

I hope some of the services (slitherine support or Plimus) will solve the problem soon, but as other people say... I'm used to get the games in Steam, and have to wait for a "human" responese is annoying!

Anyway... thanks in advance.