No you dont. It would be silly if you needed a license to open or concealed carry on your own property. That would make it impossible for most Californians to perform gun maintenance at home or defend themselves from an intruder.
If you wanna go straight to the source, section 26035 of the CA Penal Code is a good start:
"Nothing in Section 25850 shall prevent any person engaged in any lawful business... or any officer, employee, or agent authorized by that person for lawful purposes connected with that business, from having a loaded firearm within the person’s place of business"
25525 PC is also relevant as it reiterates the home & business exemption to concealed carry laws
The problem is you're looking at one statute in isolation and not how courts have interpreted it in concert with other statutes.
Yes, sometimes you can lawfully open or concealed carry on your own property without needing a permit. But if it's open to the public, you need a permit.