Install button not working (third party app) on Nexus 5X

I am unable to click on install button. I have made back up some of my apps. But now when I'm clicking on the install button, it's not working. Cancel button is working nicely. I purchased it 3 days ago. I didn't install any app that is related to screen brightness. I googled for this problem, I found an issue with screen brightness app. I didn't install any kind of these apps. I'm using Marshmallow 6.0.
Any suggestion please.