That package drops a pile of ready-made PPD files, including one for the LabelWriter Duo, into /usr/share/ppd/. After it finishes:
Plug the printer in and open Settings - Printers - Add (or run system-config-printer).
Ubuntu should spot the LabelWriter and automatically pick the right “DYMO LabelWriter Duo” entry from the list.
Print a test label to confirm.
What was that “drv:///sample.drv/dymo.ppd” thing?
CUPS can build a temporary PPD from its own sample driver database; the odd-looking URL simply tells CUPS, generate a DYMO PPD on the fly. Installing the real printer-driver-dymo package gives you the full, maintained driver instead.
That’s all there is to it no hunting around the web for random files. Enjoy your labels!
You solved my problem. I went to settings/printers and found it but had no idea what to do. I did as you said, and evidently it worked just fine and now I can see how my labelwriter duo works!