To set up a funnel on Pipedrive for SaaS (integration) sales, first of all you have to define Stages (based on your Sales Journey).
Example for a self-service platform with trials:
• New Lead (user signs up)
• Trial Activated
• Engaged in Trial (specific feature usage or milestone reached)
• Conversion Opportunity (trial nearing end, interest shown)
• Closed-Won/Lost

This is the basic.

After that, you can build it in Pipedrive and leverage Pipedrive Automations.
To do that you can create workflows to move users through stages based on their actions (e.g., “Trial Activated” triggers when a trial account is created).
Remember to use automated reminders to follow up with engaged users nearing trial expiration. ;)