It doesn't work on all hardware, do not ask why, I am lucky user, GNOME work on old AMD hardware from 2008. 
4 GB RAM, first install failed, second work.
So do not use any software other than calamares.
I make first screenshot, open terminal, open file browser, use neofetch.
First install, I move away from PC, show not "All done". Calamares was closed.
Second install, without using apps, work fine. All done window, reboot, work.
2.88 GB? 
???
My nice old grey-blue eyes don't saw this value .
Point me, but unused RAM is always wasted RAM 
Ahh, maybe I open Firefox, then we know why it is a little more
I point to System space (partition)
So you had pretty much the same experience than last time. I suspect Calamares got killed first time as there were "quite a lot" of things running for a 4GB install with Calamares which needs a lot of RAM to do its job. 
