In order to connect Salesforce data sources in Funnel your Salesforce user needs a profile that:
Can connect custom applications to the Salesforce org.
Has read access to the specific object you are connecting to (e.g. Lead or Company).
(in SF Org: Setup > Users > Profile > Object Settings).
Has API access enabled.
(In SF Org: Setup > Users > Profile > System Permissions > API Enabled)