How to install MAC OS X Yosemite Beta 4?

Question

macOS

Hello!
Actually the problem is -
On top of 10.9 I also installed DP 1 Yosemite and updated the axis with each new beta without any problems, beta 4 came out last, and as usual I updated it. The system asked to reboot to install updates. And in the reboot, the update scale at 20% does not go to the end and then the computer turns on.
Safe mode won't turn on.
I tried to enter the backup menu via the time machine when booting via CMD + R, but I don’t have a backup there and there is a second menu “Reinstall Yosemite 10.10” I press reinstall, it says that I don’t have any rights, I wanted to know what rights ?
Or does it ask for a developer account? I don't have a developer account. I also downloaded the DP version from the torrent. but before BETA 4 everything was updated without problems. Now, I do not know what to do, how to roll back or fix errors. Another question, if I download beta 3 or 4 again and install via a USB flash drive, will the user files be deleted?