Hi, you don't have to be working in an audit firm or a pvt firm to be eligible to apply. People work as auditors and accountants in a variety of sectors such as schools, manufacturing companies, audit firms, consultancies, hospitals, government ministries and departments, even in the military! It doesnt matter where you work but what you do and if you can get a reference letter spelling your roles from your employer(s).
So please go ahead and apply now if your current responsibilities match your chosen NOC (your experience from both audit and accounting will count in your favor). Good luck with your application