Teamup Calendar does not have a specific integration with Quickbooks.
However, Teamup Calendar does have a public API. Using the API it is possible to read, write, update, and delete calendar events. This enables you to set up your own custom integrations between Teamup and other systems and applications, such as Quickbooks Online.
Another option is to use a service such as Zapier to set up an integration between Teamup and Quickbooks Online. See here for an overview of how the integration could work.
For example, when an event is created or updated in Teamup it can trigger a new invoice in Quickbooks:

More information: