I purchased the founder’s edition of the game via steam and have not received the ability to pre-download the game. Not sure if this is a bug or not, help would be appreciated.
most people have had success with simply restarting their steam client. Some people mention removing it from favorites tab if its there and then restarting.
I hope this helps 
I had the same problem. Just restarting didn’t help. I had previously participated in some technical alpha test and had the Lost Ark client already in my List of installed games.
When I removed Lost Ark from the list (by right clicking and selecting “remove from installed”), the new technical beta client appeared in the list of installable games and now I can download it. Restart wasn’t required at this point.
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