Integrate your Harvest account with Proposify by selecting the account settings and then click on the Harvest logo.
From there, enter your Harvest subdomain (eg: if it's 'yourcompany.harvestapp.com' then enter 'your company' in the text input)
Click Login and it will ask if you to give Proposify permission to access your Harvest account.
Click approve and you'll be re-directed back to Proposify.
After a proposal has been marked as Won, you can create a project and generate an invoice in Harvest, by selecting the Harvest button at the top of the Proposal Snapshot page.
You can then create a project by selecting a start and end date, as well as inviting teammates to the project. Then select View Project.
You can generate an invoice by selecting a percentage of the proposal to invoice and clicking Generate Invoice.