I'm trying to use the unified search url below and I get a 403 error even though I'm logged into our zendesk hub:
/api/v2/guide/search?filter[locales]=en-us
If I try the article search /api/v2/help_center/articles/search, it works fine.
Is there a setting I'm missing?

Are you making the requests through something like postman or curl, or a different method? Also, the Search API requires light agent, agent, or admin access privileges. Can you confirm that the credentials passed in the request meet these requirements?
Thanks!
Tipene