Zapier can't quite do something we'd like, so would like to try Make.  We need API key to establish connection.  We're on Creator plan.  Is this possible without upgrading?

API Access is available only on Creator pro and above

Might it be possible to have setup for Make like that for Zapier...someday when v5 is good?

We would not make APIs available on creator for v5, no. You would require creator pro