After Effects CC 2015 (13.6.1) stalls loading on my MacBook Pro.
Adobe is getting very sloppy lately with updates. I prefer fewer releases that are thoroughly tested...
Try signing out of your Creative Cloud account, rebooting your computer, then signing back in and trying the update.
If that fails, uninstall AE, then reinstall and update. (If you have older versions on your machine, make sure you don't let the CC app remove the old versions as it defaults to do.)