How can I download the extension for my app

MIT App Inventor Help
1

Please tell me

2

what extension? Download the aix file and in the Designer, at the bottom of the Palette, you have an "extension" section where you can import that aix file. Then, drag it like a normal component.

3

See the App Inventor Extensions document about how to use an App Inventor Extension
Taifun

4

If you do not have aix file,
Download it from here :

If you have the aix file Install it like this below :

5