[Designer/Publisher not saving into Applications]

Hello.  I am new to the Affinity Suite.  I have poked around the forum and FAQ but do not see my question.

I have successfully downloaded and used Designer and Publisher on my Mac.  Everything seemed in order until we had a power failure.  When I restarted computer Designer/Publisher were no where to be found.  I searched Applications and my Mac every way I could think of with no luck.  Definitely not in Applications where it was supposed to be.  I re-downloaded and a week later - another power failure and another disappearing act.  In this case I still had the Designer installer on my Mac so I reinstalled (I believe everything in order and files recovered)

I assume we are not required to download every time the applications shuts down? (I live rural and have slow and limited internet and frequent power failures!) or install every time our computers are shut down.  

Any advice appreciated. Am I not installing properly?  Thank you!