Thank you for writing this up in detail and providing the screenshot, @Primavera.

QuickBooks Self-Employed has a different website that's why you're unable to see the subscription in the Pro Advisor Discount billing section. At this point, to connect your QuickBooks Self-Employed client, they must invite you as the user to manage their account.

You can share these steps with your client:

1. Click on the Gear icon.
2. Under About you, choose Accountant.
3. Enter the accountant's email address.
4. Select Send invitation.
5. Once you see a confirmation display “Your accountant was invited”, click Done. 

For more information about the process, provide this article: Invite an accountant to review your accounting in QuickBooks Self-Employed.

Once you receive the invitation, you can now access their QBSE account through QuickBooks Online Accountant. To access the client data, follow the steps below:

1. From the Navigator menu, select Your Practice then, Clients. 
2. Within the Bookkeeping Status column, click the QuickBooks icon that corresponds with the client or company file you are looking to open.
3. Then review and make edits to their books.

I've got these articles for further insights about QuickBooks Self-Employed:

• QuickBooks Self-Employed Overview
• Sending info to accountants

Additionally, you can read through these articles on how to keep track of clients and update your client list:

• Manage clients in QuickBooks Online Accountant
• Manage your wholesale discount plan and wholesale discount clients
• Add clients to QuickBooks Online Accountant

Stay in touch with us if you need further assistance in adding a client or any QuickBooks concerns. We're always around to assist you anytime. Have a great day!