I'm experimenting with some download managers on Ubuntu, and I think uget + aria2 is very good in terms of speed.
So I decided to make a queue and download those files using uget, with aria2 plugin enabled. However, the queue is not auto-downloading, ie the downloading stops after one file finishes. It should go to the next download automatically.
Note: What I want is to download a queue one by one (so I change the active download to one, one file at a time), not download them all at the same time.
I am not quite sure what your issue is but you need to edit the settings for whatever category you are using to limit the amount of active downloads at a time.
[1.] Right click the name of the Category and choose "Properties".
[2.] By default the settings will list "3 as the Active Downloads".
[3.] Change that to "1" and it should work like you want it to.