Download of usbdrv233.zip from
Hobbes incoming works. For a special OS/2 Mozilla version, you have to Ctrl+drag the https link to a local folder. Trying to save it via context menu won't work for the combination Hobbes and that OS/2 Mozilla version.
You can also use this link:
Hobbes incoming.
Then the usbdrv233.txt file gets visible. Download works as well, but it has 0 B.
About the rename option in incoming: That used to work only within a limited time frame, I seem to remember that was a few hours only. Note that the browse, download and upload facilities are currently being worked on, as Martin already wrote. If you have already written an email to the maintainer, that's all you can do for now. He usually answers.