The adserver will automatically try to collect the amount of pageviews for each website. The pageviews will be counted for calls to placement codes of type script, async. script, iframe and amp as well as for calls to website container codes.
How are PageViews different from (Ad-)Views?
A pageview will always only be counted once per page. If a website contains 3 placements, the adserver will count 3 requests and potentially 3 (ad)views but only 1 pageview.
How are PageViews reported?
Pageviews are only counted per website and not per placement and/or creative, hence pageviews will only be reported if you do not group by advertiser, campaign, creative or placement.