I would definitely suggest taking a look at the link @BlackJack posted for Roon installation instructions: Installing Roon on OSX.
You mentioned that you see the Roon logo pop up and a white screen. If Roon is not opening at all, I would double check to make sure that you have the correct permissions for Roon to run. As mentioned in the article:
On occasion, Roon may not have the correct permissions to run on OS X. If you attempt to launch Roon and the icon bounces but Roon never opens, your permissions may not be set up correctly. To fix this, first make sure Roon is not running. Then, you’ll need to open Terminal, then, just copy this command (CMD+C) and then paste it into the terminal window (CMD+V):
If that does not work, I would next check the font permissions:
If you’re still having issues, it may be related to OS X’s enabled fonts.To fix the issue, open the application “Font Book” on your Mac. When you open “Font Book” you’ll notice that some fonts or styles are grayed out and say “Off”, which prevents applications from accessing those fonts. Right click Arial in the list, and click Enable. This will give Roon access to Arial and your next launch should be successful.
Can you let me know if you have any antivirus applications which could be blocking Roon from operating properly? In the past we have seen issues with Bullguard, Little Snitch, McAfee and Norton interrupting the regular usage of Roon.
I would check to see if there is any change in behavior with your antivirus temporarily disabled, and if there is we know to take a closer look in that direction. I would also make sure that both Roon and RAATServer are added as exceptions to the OSX firewall by following these instructions.
Please let me know if any of my above suggestions help with launching Roon.