It is the classic double speak which makes absolutely no sense. Always replace the word Zionist with Nazi to find out how ridiculous it sounds “I am not a Nazi but I support Nazism”. That is what we call a Nazi.

Is it just the belief of the right of a self deterministic Jewish state

This is not what Israel or Zionism is. There is a crucial word missing: exclusive.

“The realization of the right to national self-determination in the State of Israel is exclusive to the Jewish People.”