You’d like to access to Google Webmaster Tools account of a client and you rather avoid complicated procedures. Ad Performance makes this authentication process extremely simple. All you need to do is email the special link. This video shows the process in detail; - Go to Channel Settings, click on “Let External Person Grant Access” button. - Email the special link that appears on your screen - Your client clicks on the link and completes the authentication and give you access. Simplest way of granting / receiving access from a client or third party.