SS stands for Social security number. Every US citizen has one that identifies him or her so he or she can if need be get assistants from the government, etc. It also identifies you for taxes.
The social security number format will be something like this 123-456-789.
The Corp ID#/ABN is a corporation's tax code that is given to every US business to identify them for tax puposes. It's format is like this, 12-3456789.
You could fake both of these, however some of the CPA companies will check. Just a word of advice. If you do fake any information on any application with any of the CPA companies, or any company for that matter, you are committing fraud. Once they find out (and they will find out, trust me on this one), they will immediately withhold all your earnings. Of course they will let you earn and earn and earn for them first, then refuse to pay you. Hope this helps.