You need to
Enable From Unknow Sources on your TCL TV. For more detailed steps, refer to
How to Download an App on TCL Smart TV.
1. Download Apps from App Store
Every smart TV has its own application store, and some will pre-install many apps even live apps, and some do not. When you buy a new TV, visit the App Store to see if it already offers the app you want. If there is, you can directly click the icon and install it.
2. Install Apps via USB
You can save the APP downloaded from the computer to a U disk or SD card, and insert it into the corresponding interface of the TV. Then, you can choose the file manager to open the APP, or you can read it with the ES browser. Just click on the app file and it can be installed on your smart TV.
3. Download Apps with App Tool
To help TV users install apps on smart TVs, developers provide many tools to download apps. For example, in the guide on How to Download Apps on Sony Smart TV, people use Send files to TV to send apps from a smartphone to a TV.