Hi there, rainlarkbooks-gm.
If you're the accountant and you're the one created your client's new QBSE account, you can add your client to your list so they can access their new account . Please make sure that your client's contact information are correct. I've added screenshot for your visual guide:
Once done, have your client accept the invitation for him/her to start working his/her account.
I'm including this article for reference: QuickBooks Self-Employed Overview
I'll be right here if you have any follow up questions.