As Atlassian sells the draw.io on the Atlassian Marketplace, they must provide you with a quote. You can generate a quote via the Marketplace.
- Go to https://marketplace.atlassian.com/plugins/com.mxgraph.confluence.plugins.diagramly/server/overview.
- Click on Buy it now. Select Server then click Buy now.
- Select Quote and fill in the details of your purchase. Click Add to quote and submit the form to Atlassian.