Built, not switched on yet. DocFila cannot read or send from your Gmail account yet. The connection and the send step are built, but they need Google's approval for Gmail access, which DocFila does not have.
Nothing is read from or sent to Gmail. Save an attachment to your device and open it with DocFila; send a finished PDF from DocFila's share sheet.
There is no single Integrations screen. Cloud storage is in Settings › Cloud Sync and in a team workspace's Connectors tab. Slack, Gmail and Salesforce sign-in is in an organization's Settings. Accounting exports are in FinFlow › Reports. Outbound webhooks are an action in Tools › Workflows.
Keep going with the document workflow that matches this page. Open the tool you need, then finish the file in DocFila.