Looks like the author is still active and looking for funding: https://github.com/TachibanaGeneralLaboratories/download-navi
But development seems to have stopped indeed. There is a fork, with new developers, that is actively being worked on: https://github.com/Davilarek/download-navi
Not sure I would call that “active”. No activity in over a year. And even that was just changing a couple markdown files.
For offline software I wouldn’t consider it a problem, but for something that connects to the internet I would want it to have the latest versions of its dependencies.
It looks like the dev has been updating their funding details recently, hopefully they have an update planned.
https://github.com/TachibanaGeneralLaboratories/download-navi/commits/master/