Hello @JamesRong
Thank you for contacting the Instructure Community. We're sorry to hear you've been experiencing issues with setting up Veracross with Canvas. That guide is just an overview but you may find these guides more helpful. Here is more information for admin setup and also teachers using Veracross:
https://community.canvaslms.com/t5/Veracross-and-Canvas/tkb-p/veracross_and_canvas
Beyond that, you're going to want to set up the SIS following this guide:
How do I manage student information system (SIS) i... - Instructure Community
If neither of those are helpful, then you'll want to speak with Canvas Support directly. Either Support can assist you in setting it up or they may send the information to a CSM (designated support for setting up SIS, LTIs, account changes, etc.) and they can assist you from there.
How do I contact Canvas Support? - Instructure Community