I don't know either what the mt4sock numbers mean, but will inquire. Pepperstone is a relatively well known broker and we have not yet heard of this problem, but maybe they have changed their account creation method recently.

Update: The numbers reflect the MT4 and account version, and here 03 and 13 are indeed for a demo and a real account. "Access denied" means that the account type does not match the type in the Zorro scrollbox. When Pepperstone does not allow to open true MT4 demo accounts, you cannot trade with it with the free version. You need Zorro S. Or a different broker.

We'll check if there's a workaround with Pepperstone, and otherwise mention this problem more clearly in the manual.