Hello there. Please note that QuickBooks Self-Employed does not support vendor management, which is why the connection link for Sherwin is unable to load into your account. This software is designed primarily for tracking income and expenses for tax purposes by using your linked bank and credit card accounts.
The Sherwin’s quick link you mentioned to add to QuickBooks is for QuickBooks versions that support vendors, like QuickBooks Online. You may want to transition to this program, where you can add vendors and use integrations. Otherwise, the workaround in QuickBooks Self-Employed is to use the Description field of the transaction to identify Sherwin on each expense. Then, manually categorize those transactions.
I’ll keep this conversation available for any follow-up updates or questions.