I can't use Zotero
We have a job (shared document) in Google Doc and every time I try to link a cite and use Zotero, the cite in the docs change to color red. I already have the Google extension and the downloaded application, both with my account. And my other colleagues have also done the same, but the error persists.
Upgrade Storage
Are you referring to unlinked citations? You get the warning that citations in the document are no longer linked to your library?
That's almost certainly not due to the action you're taking now but due to something that happened previously — Zotero simply warns you about the existing brokenness when it goes to refresh the document.
See https://www.zotero.org/support/kb/google_docs_citations_unlinked for the known causes and fix.