> I find JDownloader2 to be very scammy feeling. It feels like adware software.

That's because it's not in fact open source. From Wikipedia:

> Some parts, but not all, of JDownloader are open-source.

> Mid-2012 there were complaints that JDownloader's installer added adware without the user's consent.[4] The JDownloader installation contains adware according to several sources, including the developer's own forums.[5][6] There were further complaints mid-2014.

JD is basically junkware. There's a reason why it doesn't seem to be packaged on any Linux distribution. It's not community-focused OSS in the ordinary sense.