Alternatively, if you navigate to My Settings via the settings cog, you can invite colleagues from the Team Members section.

You can only invite colleagues from a listed domain on your account. The primary email domain will be from the email address you used to create your Polytag account and you control the domains associated with your account. Head over to My Settings, and then the Domains page. You can add and delete domains here. For example, you may want to invite a designer to build you some landing pages, so you would add the domain (e.g. timsdesigns.com) so that you can then invite [email protected]