Am I qualified to participate if I only have 3~4 number years of HR experience?

You will qualify if you have 2 years of HR-related work experience at the relevant seniority levels. For Example:
 

As an IHRP-CP, you will need 2 years’ experience at the relevant level as stated in the Body of Competencies.
 

As an IHRP-SP, you will need 2 years’ experience performing in the scope of a Head of HR, HR Director, HR Business Partner Lead, or equivalent.