First, you share the business context, website, markets, approximate spend and the main concern. We agree the account or accounts, reporting period and review areas. Access is arranged through the advertising and measurement platforms; you retain account ownership.
I inspect the available evidence, compare the campaigns with the website and measurement, and prepare the findings in an order that helps you decide what to do next. Your feedback on product economics or qualified leads helps separate a reporting problem from a commercial problem.
I need enough history to assess the question, but I do not ask you to email passwords. Where access is incomplete, we agree whether the review can still answer the useful questions.