From Connections, choose QuickBooks and sign in with your Intuit account. The connection supports QuickBooks Online; if you run Desktop, tell us in onboarding rather than connecting a mismatched account.
What is granted at connection: read-only access to customers, invoices, estimates, payments, and aging. This is what lets the queue prepare invoice drafts with real amounts and drafts payment reminders against live balances. Nothing at this stage can write to your books.
When writes happen: the first time you approve an action that posts to QuickBooks (an invoice, a customer record), flo.space requests the specific write permission it needs. After that, writes still only occur as individually approved actions; there is no background sync writing to your books.
Good first week: connect the inbox too. The highest-value QuickBooks drafts (invoices from agreed threads, reminders in the original conversation) need both sides; the Gmail + QuickBooks page shows the combined flow, and the invoice template is the flagship workflow.