Your Klaviyo user needs to be an Admin, Owner, or Manager to manage integrations in Klaviyo. Therefore, you need this role to be able to create a Klaviyo data source in Funnel.
When comparing data in Klaviyo with Funnel using the Klaviyo Dashboard you might find what seems to be data mismatches. This is because Klaviyo attributes revenue differently in many of their analytics views. In most views Klaviyo attributes the revenue to the date of the last email sent. However, when Funnel request the data from the Klaviyo API, we get Placed Order and Placed order value attributed to the date the order was made. This data corresponds to what you find in Klaviyo's Metrics view, which is where the comparison needs to be made.
However, the Klaviyo Metrics view does not always contain all data if the data amount is too large. To be able to do a full compare with Funnel you might have to create a Custom report and export the data.
Both the Metrics view and Custom report are available under Analytics in Klaviyo: