Ploegie wrote
With the Roundbox template the "mediamanager" button is missing (down right in the default template).
As turnermm pointed out, this was not integrated into the roundbox template yet. (The fullscreen media manager was only added to the latest version, "Angua".) But the popup media manager still works and you should be able to handle all media through that one.
Ploegie wrote
When trying to upload media in pages also the "select files" button is missing.
It's not missing, it just doesn't look like a button (also due to changes in Angua). Just click "Select files..." (the text).