This app sends notifications from apps from your Android device to Windows device. It is somehow similar to "Your phone" application from Microsoft, but also have some differences:
1. It can send notification also from tablets and from Android Go edition (Your phone cannot be installed on such devices)
2. You can add filters (so not every notification is sent to Windows)
3. Notification are sent to your OneDrive, and can be read on any device (companion app is for any UWP device, e.g. Lumia phone; but it can be read even without any app from any device with WWW browser connected to Internet )
4. Notifications from more than one Android device could be send to Windows device
5. And notification from Android devices can be read on many Windows devices.

But, there is no ability (yet?) to respond to notification via Windows device.

App creates log file (for debug purposes - if you encounter some problems, you can send me this log) locally, but all other files stores on OneDrive (Apps/Andro2UWP folder). These files are:
* notifications (or, in UWP parlance, toasts) - files *.toast.txt, created by Android app;
* sender.renames.txt, created by UWP companion app;
* toasts.filters.txt, created by UWP companion app;

Format of sender.renames.txt:
original.sender.name|renamed.sender

E.g.:
com.whatsapp|WhatsApp
com.bigajwcislo.ostrzegator|o!strzegator

Format of toast.filters.txt:
sender|title|text
you can prefix (or sufix) text/title with '*' (mask character).

E.g.:
com.microsoft.skydrive|Preparing...|
android|* is using battery|
com.google.android.music|Downloading…|
com.whatsapp||WhatsApp Web is currently active