http://www.anime-sharing.com/forum/hentai-cg-packs-24/%E3%80%90143008%E3%80%91%5Bhcg%5D%5Bred-paprika%5D-%E6%81%A5%E8%BE%B1%E3%81%AE%E3%83%88%E3%83%AD%E3%83%BC%E3%83%AB%E3%83%90%E3%82%B9%E3%82%BF%E3%83%BC%E3%82%BA-%5Brj140426%5D-353077/
This one has the game.
I'm experiencing the same issue with the game crashing on startup, but I don't think the problem is the download itself. Try it yourself: see if you can run the trial version of the game, which you can find on the dlsite link you provided.
The one solution I know of is to copy main.swf from...
I spent a few hours scouring the internet for a solution and a few places mentioned that you need something to crack the drm application. I have found one of those cracks, and it works for me. However, it looks kind of shady so I wouldn't blame you for being hesitant...