Why is this app so slow at downloading?

I recently started using Dropsync , and it does exactly what I'd like it to do in terms of syncing my MP3 collection by automatically downloading when I've added new songs. I bought the pro version.

Unfortunately, the one problem is that it's very slow. I have a new wireless router, a gigabit internet connection, a Galaxy S5, and Android 5.0. I just ran a speed test app, and it showed me getting a download speed of 20 Mbps. And yet, Dropsync downloads consistently around merely 90 KBs .

I've contacted the developers, but they haven't responded at all, and I've seen mention on the web here and there that this developer is notorious for not responding.

But, even still, I can't imagine how or why an app would throttle downloads, even by accident.

I have two questions: Is there a setting or something I should be looking at which might be holding Dropsync back (there's nothing in the Dropsync settings that I can see)?

If Dropsync can not be made to download at speeds more consistent with what my wifi is capable of, is there another app that does a similar function that is not so slow?