Hello and welcome,
What Qubes OS version are you trying of installing ?
What computer are you using ?
From the error message you quote, the system hasn’t been able to start
sys-usb. The installation might be fine.
See if you can boot in to Qubes, and then check the devices attached to
sys-usb. You may find that they need some special treatment, or that you
need to add some other devices.
(If you have more than 1 controller, start with only 1 and get that
working. Then either assign another to another usbqube,or add it to the
existing usb qube.)
version:qubes os 4.0.4
computer：Lenovo x230 i5-2520 4GB
don’t use sys-usb it’s okay. you may face lag issue because amount of ram, but it’s good start 
try to learn more about qubes is more important.
I guess you won’t go very far with 4GB of RAM. I would recomend 16, but 8 might work (with some work and limitations)
I changed 8GB of RAM.And I started a new application.A new error came out.
Qube Status: anon-whonix
Domain anon-wholx has failed to start:internal error: libxenlight failed to create newdomain 'anon-whonix
Just to confirm where the issues lie, make sure you can start sys-net
and sys-firewall, and then start a clearnet qube which has the netvm set to
sys-firewall. (You can change the netvm in the Qube Manager settings for
each qube.)
See if you can start the vault, which has no netvm.
If you can do this then you have 4 qubes running.
Work in those qubes and then see if you can open another qube attached
to sys-firewall. And so on. You’ll find a pain point soon enough.
Even 8GB will be tight, and need fine tuning. Qubes will try to adjust
the memory available to each qube when they are running, but in my
experience this often doesn’t happen when you are trying to open a new
qube.
You can find threads on managing memory here in the forum - minimise
the amount allocated to dom0, reduce the RAM requirements for your
appVMs. It’s been covered before, and you should be able to find advice.
That said, Whonix is a resource hog when things are tight.
I had a very similar error, but then the Qube started up anyway. I’m not sure whether @unman or anyone else on the team wants to review my libxl-driver.log to see if there is an actual problem.