⏬ Download the archive with the extension.
Unpack it to any folder
In the Google Chrome browser open the “Extension” page. There are several ways to do this:
chrome://extensions in the address bar of a browser and press Enter.
From the menu: click the three vertical dots in the upper right corner (near the profile picture), then "More Tools", then "Extensions".
Or go to the Google Chrome settings and select "Extensions" (at the very bottom) in the right menu
Enable “Developer Mode”
Then click on “Load unpacked”
Find and choose the folder where you unpacked the extension.
After that the extension should appear in the list of the installed extensions.