The tool works fine.
It took me a while to install it on MS365.

After I got these instrucions from the support ist worked fine:
https://support.newoldstamp.com/en/articles/5967487-how-to-register-the-microsoft-graph-app-on-the-microsoft-azure-portal

https://support.newoldstamp.com/en/articles/5967613-how-to-install-microsoft-add-in-centrally-mobile-devices-covered

It could have some more design option like:
- Choosing more icons for all apps
- Margin options for profilepictures
- Inserting not only timed promotion Banners, but also timed html boxes or Text boxes
- MOST IMPORTANT: Chance to Insert a spacing at the top, so that when you start writing with your email client, the Text don't sticks to the signature. Right now I have to add at first a few line brakes, the go to the top to start writing. this is a bit annoying.

But appart from that it works fine.