Not possible to create Relive videos on the PC
Videos can only be created using the Relive mobile app, which is available for both iOS and Android devices.
Currently, Relive does not offer a desktop app or functionality for creating or editing videos on the Relive website.
To transform your activities into epic videos, you'll need to use the Relive app on your phone. The website, however, allows you to download GPX files, update your account settings, and explore more information about Relive.
At this time, there are no plans to release a desktop app version.