I am also trying to get my package uploaded to extras-devel (non-free). I did:
which appeared successful. The .upload file showed that the *.deb, and *.changes, files were uploaded successfully.

I followed the instructions on the wiki page, including getting a garage account, an invitation, and a public SSH key.

Will I get an email indicating if my package uploaded, or what errors were there?

Also, does Extras Assistant work for non-free packages, or just free ones? Should I use that instead?

Thanks for any help.

EDIT - Looks like I was just impatient - package is in extras-devel. I guess they get loaded there on a set frequency of 1 hour.