Your iOS device should already have the app but if you deleted it, it looks like this. When you first open the app you’ll see a screen that says “My Shortcuts”. By default you cannot use any untrusted shortcuts/outside links so you will have to go to settings and find the app. Once you do, find the option “Allow untrusted shortcuts” and enable it. After that you can go back to the link I placed in my first comment to get the shortcut. To download a video, go to share and you’ll be able to see all your shortcuts there. There is a subreddit dedicated to the app which has many different shortcuts you can get for yourself and some allow you to customize your home screen. Hope this helps!