Apps from unknown sources

[Psalmist]

Just purchased a Samsung Qe55q60c. Delighted with the picture, etc. But have tried repeatedly to install mfc app - via firestick - without success. Have downloaded the app to the stick via downloader, then receive this message:

for your security your TV is not allowed to install unknown apps from this source.

I have seen numerous suggestions via google as to disabling the restriction on apps from unknown sources but none seem to apply to this TV with Tizen os - aside from a few that look to require serious IT ability. Any help would be very much appreciated.

[MorningBlunt]

Should be fine if using fire stick. As far as I know, there's no workaround for installing directly onto TV.