that's a tricky one...
the answer may be in the line
Subsidised fees are available to EU Nationals only i.e. students who have EU nationality or who hold an EU passport:
Having stamp 4 makes you a resident in the state, but you are still not a holder of an EU passport. You can work without a work permit, apply for social and affordable housing, mortgage, social welfare, etc. that would be the meaning of
long-term residence permits, giving to the holder rights in
the State similar in most respects to those of Irish citizens.
I guess you should enquire that at the college/university where you want to study and ask them whether stamp 4 would suffice for the subsidised courses.