All of the templates are customizable in Canva.
You can use the free version of Canva to edit the templates, and there are lots of free stock photos, design elements, and animated gifs for you to choose from, and of course you can upload your own photos! You'll be able to download the animated video mock-ups you create as static images (.png or .jpg) or as videos (.mp4).
For even more awesome features, I recommend upgrading to the Canva Pro account, including uploading your branding colours + fonts, lots more stock photos and design elements, "magic resize", and more...and you'll need Canva Pro for downloading files as .gifs (to insert into your email newsletter).
You should know the basics of Canva to successfully update and edit this template.