This seems like the same question, so let’s keep it in one thread, okay?
The folder called addons21 has a folder for each of your add-ons (“named” with the add-on’s code from the shared site). If you put all of those folders in the same place on your fresh system (%APPDATA%\Anki2\addons21), while Anki is not running, those add-ons will all be installed and available to Anki. You don’t have to open any of them. Hopefully you have the whole addons21 folder and you can just plop that all in there at once.
However, if you are installing a different version of Anki – not all of your add-ons will necessarily work. You’ll have to check each of them to see which has been updated, and you should disable the ones that haven’t been.