Just download it https://codestation.github.io/qcma/
(Scroll down to the download section)
Turn off your wifi on your psvita and reboot it. Then proceed to connect it to your pc.
then restart your vita, no internet, turn on offline mode in qcma, make sure the vita version in qcma is the highest it can go.
It's a bit weird. I was getting that too. So I put a 3.60 update.pup and psp2-update.xml (with correct region) into QCMA PSV Updates folder, DISABLED Offline Mode, and ENABLED Airplane mode on Vita. Rebooted Vita, connected it and it worked.All I get is "could not connect to pc"