Hello Nikola,
we bought the ical extension and it looks good so far. The only problem is that we can't add linebreaks to the ical summary.
As mentioned here \n is not working because its gets escaped.
Is this really fixed as you told 3 years ago in this post? What am I doing wrong?
It might be fixed by adding a textarea instead of text input.

Also, it would be nice to have the option to send the ical file only to the admin and not to the customer. I fixed this by removing the filter whichs adds the attachment for users. But i think it would be nice to have this without custom code.

Thanks and best regards Aaron