Can't install apk files on android lollipop v5.1

[AC Question]

Can't install apk files on android lollipop v5.1
mobile name lava iris x8 (2 gb of ram0

 

[B. Diddy]

Welcome to Android Central! Go to Settings>Security, and make sure Unknown Sources is turned on.

Be careful with apk files. The sites where you can find them aren't typically regulated, so they can be teeming with malware. The apk files may also be pirated, which we strongly discourage.