I can not install my downloaded "particle logo reveal" animated logo

hello there
I have jsut bought “particle logo reveal”; When I try to download it, it says there is no app to do so and App store referes to the file as unsave to open from an unidentified developer.
How can I open it being it safe?
thank you for your help

Is this the item?

If so, you’ll need both Adobe After Effects and the plugin Trapcode Particular to use it, as it says in the item description and technical info.

All items are reviewed before showing up in the marketplace, so there shouldn’t be any security issues with it or any other item.