A few people have run into a glitch just after installing Lightroom CC. The install finishes normally, and then when you try to start Lightroom, it flashes on the screen then almost immediately disappears. It looks like a crash, but as best I can tell it’s actually license authentication that’s failing.
If this is happening to you, simply log out then back in on your Creative Cloud utility. It’s not enough to exit and restart, you must log out by going to the gear icon in the upper right > Preferences… > Sign Out.