Okay so I encountered this problem as well I called samsung support and a supper helpful guy named Edgar told me I had to reset the tv and of course I didn't know how to do that, so what we need to do if you can't install an app you have to press and hold the power button and continue to hold the power button until the tv turns off and back on and this will effectively reset the TV but WON'T DELETE ANYTHING so don't be scared I then went back to install the app and it installed right away, I hope this works for you.
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