Open this page in Google Chrome or Microsoft Edge on your computer.
Look at the right end of the address bar for a small install icon (a screen with a down arrow) and click it.
Click Install. ClipStudio opens in its own window and gets an icon on your desktop and taskbar.
Next time, just double-click the ClipStudio icon. Log in with your email and password.
Can't see the install icon? In Chrome click the ⋮ menu (top right) → Cast, save and share → Install page as app… (or Install ClipStudio). In Edge click ⋯ → Apps → Install this site as an app.
The app needs an internet connection to log in. Your videos stay on your own computer and are never uploaded.