MacOS – Cannot not install application from App Store on macos mojave

I am a new Mac user and have purchased a Mac Pro 5,1 running Mojave to learn the basics of macOSX.

After some initial difficulty, I have logged on to the mac, created an appleid, added payment details, signed on to the (Macosx) app store and itunes under mojave.

In the apple App store I selected to install two free apps I use under MS-Windows: Microsoft OneNote and OneDrive. There were a whole array of problems trying to install this way. However, I have now got to the point where app store shows these two applications as "Purchased" but they are not installed on the mac. I have several times tried to redownload the apps but they do not install and no install materials appear in the Download folder. There are no diagnostic / error messages indicating a problem – just no installing occurs.

I cannot find on the mac the apps I have "purchased" (they are free but marked as "purchased" in App Store) in either the Applications folder or in the Launcher. The way I can describe the behaviour it is like I have had my order for the OSX applications accepted by App Store but they haven't been delivered to my mac pro.

I have rebooted the macPro about 4 times and retried the "installation" and nothing installs and there are no error messages from App Store.

Any ideas as how to fix?

Separately – and maybe relevant or not – I can install apps from outside the app store but cannot install apps from inside the app store. For example, I went to the OBS website, downloaded the install package, ran it, and OBS is now installed and running on the mac – easy.

Thanks.