The steps for logging in to a Shopee sub-account are as follows:

Log in to the Shopee website using the main account.

Select "Manage Sub-Account" in the "My Account" drop-down list.

Enter the login information for the sub-account, including password and username.

After clicking "Login", you can go to the main page of the sub-account, so that you can start managing orders and information for different accounts.

Please note that a sub-account can only manage store information within its authorized scope. If you do not authorize or are not authorized to use the sub-account, you will not be able to log in to the sub-account.