Uploading extension

Hi,

I can't figure out how to upload a extension in Opencart 2.0. This is the extension i want to upload
http://www.opencart.com/index.php?route ... load_id=37

When i try i am getting the invalid file type message. This is what i tried so far without succes:
- added zip and xml to the accepted file extensions
- added all MIME types i found in other forum threads
- tried with Chrome, Firefox and IEX
- tried uploading zip and uploading xml
- tried with Windows 8 and Window Vista
- filled in FTP settings (not that i think i matters)
- tried uploading other extensions

Nothing works. Any suggestions?

Upload from an Unix client or Mac.