You need an userscript manager like Tampermonkey, Violentmonkey or Greasemonkey (read the requirement details below).
Click on any script you want to install:
The script will be opened in your userscript manager. Click Install.
Chrome/Opera/Edge/Chromium browsers: Tampermonkey or Violentmonkey
Firefox: Violentmonkey, Greasemonkey or Tampermonkey
Safari: Userscripts or Tampermonkey
Android: Firefox, Yandex or Kiwi browser with Violentmonkey or Tampermonkey