Drupal 8 User Guide: 11.5. Downloading and Installing a Theme from Drupal.org

See the written version of this tutorial for links to prerequisites and related tutorials.

[aviontics]

this video is useful but there is another way to install it, click on the download link, open it when finished loading, and then extract the link into the themes folder that you should create in default, then extract it inside the themes folder then follow the tutorial after the installation process.btw i am a rookie in drupal and figured this out myself.hope this helped