Below is a step by step guide on how to accept a Landscape invitation for the first time.

WARNING: this guide is slightly outdated in the sense that the Launchpad screens should be replaced by login.ubuntu.com SSO ones. But the same idea applies, i.e., an external authentication mechanism (Launchpad before, login.ubuntu.com SSO now) is being used.

Click on the invitation url

Follow the link

Register with Launchpad

Check inbox for Launchpad e-mail confirmation

Click on confirmation link

Complete Launchpad registration

Complete Landscape registration

Welcome to Landscape!