It is not possible to upload pictures by copy and paste (we use the freeflarum.com hosting).
I use ShareX to make screenshots, edit them and optionally upload the pictures to a free picture storage server, for example imgur. ShareX provides me the picture URL which I can easily insert here:
I activated the extension imgur upload. Now you can use the upload button:
It should also be possible to use copy and paste, but this didn't work for me.
copy and paste
Please write here if there are issues with the upload. Maybe I created the Imgur application with wrong settings.