So, android 5.0.2 doesn't allow side loading of apks for 2nd user (irrespective of whether it is guest or standard user). "Unknown Sources" is disabled and is uncheckable. And I use a pure Cyanogen Mod 12 (android 5.0.2) without any Google apps. So, there is no Play Store app.
But I have root access.
As shown in the pics, Unknown Sources is Uncheckable and installation is blocked.
(Click image to enlarge)
With this situation, how can i install apks on to the 2nd user account??
It seems Google intentionally (in the name of security) blocked sideloading apks for 2nd user in android 5.0.2. There is a bug report here. And sideloading was reenabled in android 5.1.
I will post how to sideload apks on lolipop 2nd user using adb. If this can be done without adb please post.