Hi there! Sorry to confront you with some big red text like this, but you need to know that at this time, members of the WeTransfer Support team can't assist you with any issues related to our Mac app.
The app is still available to download, and should function as expected, but if something starts going haywire, we're not going to be in a position to help out. Sorry to disappoint!
Our Mac app lives in your menu bar. After downloading our app in the App Store, you will always find the app waiting for you in the top right corner.
Here, for reference: