In this post, we will discuss how we can resolve the issue which comes when you try to click on any apps you have installed. Recently after configuring SharePoint 2016 on-premise environment for Apps, when I click on any app that I have installed, it navigates to the app URL but it shows error like below.
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Authentication Required.
http://myspapps-**************.mysp.localapps:29024 requires a username and password.
Your connection to this site is not private.
It looks like below:

Open SharePoint 2016 Management Shell and run below command.
New-ItemProperty HKLM:\System\CurrentControlSet\Control\Lsa -Name “DisableLoopbackCheck” -value “1” -PropertyType dword
Now it should work fine. If it did not work, just do an IISRESET and then try again.
Hope this will be helpful.