Partner API not working. Do I need this to see all Alters?

The Partner Key I received doesn't work with the API endpoints. When I performed a WHOAMI API (with Client ID/Secret), it said I was a Tenant. My question is, do I really need a Partner Key to see all my Alters? Would I miss any Alters from different Tenants? I can view incidences from a specific Tenant, but just making sure I am not missing all of my alert messages.