My bash history (saving the commands I typed, so I can review them) was set too low - so I don’t have the exact commands that I did to configure the printer anymore.
But going by memory
and by the description in the Arch Wiki that I linked you to
which also contains a link to an Ubuntu page on how to set it up there
what I did was this:
-
install that Canon CAPT driver from AUR
-
ensure Cups is running - and is enabled
(so it will be started after reboot)
systemctl status cups.service
sudo systemctl start cups.service
sudo systemctl enable cups.service
(I think it’s enabled by default and should be already running - but make sure
don’t cut and paste all three lines at once
run each command separately - so you better see what’s happening)
- add the CAPT printer to Cups:
sudo lpadmin -p LBP2900 -m CNCUPSLBP2900CAPTK.ppd -v ccp://localhost:59687 -E
(this step above is what doesn’t work through the graphical setup tools - at least not for me
and the Wiki mentions it as well
and you need the command line later anyway …)
- then, per the description, register the CAPT driver itself via ccpdadmin
sudo ccpdadmin -p LBP2900 -o /dev/usb/lp0
- then, start and enable the CAPT daemon with:
sudo systemctl ccpd.service start
sudo systemctl ccpd.service enable
(so it will also be started after reboot …)
I hope that helps you.
ps:
there was a thread and discussion on it previously which may also help
should contain the same info and perhaps even more
it’s in german - but the english version of one of my posts is just below
The rest you’ll have to run through google translate … or ask 
the commands are highlighted and should explain a lot of it
Just out of curiosity:
what are the specs of your “crappy laptop”, my young friend?
I admire your persistence!
It took me a while and a few tries to gather the concept behind these commands
(not that that is an indication that it is difficult - but it was for me)
and to get it right and working.