Hi originally.

Welcome to the Community.

You have posted your question in the Norton Anti-Theft forum but as your question appears to be about Norton Tablet Security I will ask for it to be transferred there for better visibility and so that you can get the best possible response.  Do not worry that you may loose it as a link will remain in the original place.

I do not know why you are  unable to download Norton Tablet Security for your Galaxy Tab as I would have expected it to be compatible.  There may be a temporary problem with the "app store" so you may like to just try later and see if that solves the problem.  You do not say which "app store" and I believe that Samsung offer an app store as well as "Google Play".  Have you tried via both sources?  The other option it to try and get it directly from Norton which you should be able to do at this link.  The link assumes that you are in the US.  If you are not you may like to do a local Google search for "Norton Tablet Security".  However the above link does give the system requirements which seem to match your device.

I hope that helps.  Please come back and let us know if this has helped or not.  If not we will try again.

[Edit - sorry about overposting smithy.  We were obviously both typing at the same time!]