Pre-Selecting Tabbed Menu Items on PHP Page

I’m a UX designer who has to do some web development on a vendor’s platform. The vendor’s system is php and frequently uses iframes to place content, so I spend a lot of time trying to find ‘creative’ solutions to pages I have to build myself.

I’m creating a basic css tab menu. I need to be able to link users to this page with specific tabs open for different use cases. Our vendor says they can’t help us with this “because it’s a php page”. I feel like this should be possible, but I don’t have deep dev knowledge.

Stripped down example: https://studiotoolkit.dmplocal.com/sites/4054/tabsforhelp.html

I appreciate any suggestions. Thank you!