Left clicking should do the job, it will open up a tab but it’s going to be forced to download it somehow in the normal course of events.
The fact that it works sometimes is interesting. If you are going at the download button like a machine gun* and hitting our server several times a second, you might be hitting our flood rate prevention systems. Try waiting 1/2 hr. Click once and waiting even if nothing appears to happen immediately (your computer may have slow reactions in certain sistuations). Then once the first one has downloaded, do the same thing again.
If that doesn’t work, do you have an easier alternative, like a linux box or an android phone you could download from?
*not the trigger on the machine gun, the speed of round departure of the machine gun.