Browser says ARK-Survival Preview has been downloaded, but the XBOX One console does not have ...

It is a regional issue. The game is not available in the Netherlands.

Hello there,

The Xbox One Preview Program - getting access to new builds of the OS early for testing - is a different and separate programme from Xbox Games Preview, which allows users to download unfinished and early builds of games, such as Ark: Survival Evolved.

While the Xbox One Preview Program is only accessible by invitation, Xbox Games Preview is accessible to all users who live in certain regions* - Xbox Games Preview has only been launched in a few regions so far.

*Those regions are: Argentina, Australia, Austria, Brazil, Canada, Czech Republic, Chile, Colombia, France, Germany, Greece, Hungary, India, Ireland, Israel, Italy, Mexico, New Zealand, Portugal, Russia, Saudi Arabia, Slovakia, South Africa, Spain, Switzerland,
United Arab Emirates, United Kingdom and the United States.

If you are not in one of these regions, you will not currently be able to download or play Ark: Survival Evolved, until Xbox Games Preview expands into new markets (there's no public timetable yet for this).

Hello,

Currently, Ark: Survival Evolved is part of Xbox Games Preview, which means that the game can only be downloaded in regions in which the Games Preview programme is available. Unfortunately, Games Preview is currently unavailable in the Netherlands, so you
will be unable to download Ark until either Games Preview comes to NL or Ark is released as a full game.

Sorry about this. I know this won't be the answer you wanted to hear.

Hello JustDutch,

So unfortunately the problem is that the game is not available for download in the Netherlands. The game is part of the Game Preview programme, which has not been fully rolled out yet, and so Ark: Survival Evolved, and other games in Game Preview, are only
available for download in regions where Game Preview has been introduced.

I know this is definitely not the answer you want to hear, but I hope it helps clarify what's going on.

Hi mattjuntunen,

ARK: Survival Evolved launches today (12/16/2015) as part of the Game Preview program which actually has nothing to do with the dashboard preview. It will be available for $34.99 to all users in the Game Preview section of the
marketplace.

To reiterate: you do not need to be a member of the dashboard preview program to gain access to ARK; the the Game Preview Program is completely different and does not have a dependency on the preview dashboard group.