Did you ever apply for one? It’s not automatically issued when you apply for a corporate tax ID. You would have needed to apply for that separately on your PA 100.

If you’ve ever filed an unemployment tax return, pull an old copy and look for the account number. You aren’t going to be able to look that up online.

BTW, Etides and Mypath are completely separate entities from PA UC. Department of revenue handles corporate tax, sales tax, and state income tax withholding. Department of Labor administers PA unemployment for both the employer and employee side.