Nextcloud App not opening to show panel to configure the sync connection

Hello, I have installed the Nextcloud Desktop App but left clicking on the icon does not perform any actions - the app does not open. I would like to configure the sync options but all I see are the folders under Nextcloud on my local desktop, no app opening.

What could be the reason that causes the application not to work?

It´s a MacBook Air, macOS Mojave, version 10.14.6 and the app downloaded from Safari, version 14.0.1