As of Business Manager 1.4.0 all add-ons are included by default, and don't need to be installed separately.
First, make sure your Business Manager installation has the correct version to support the add-on. Different add-ons require different versions of Business Manager.
The Zip file with the add-on has a file structure that looks like this:
\---business-manager-[add-on_name]-[commit_hash] +---public +---updates \---readme.html
publicdirectory contains all files of the add-on.
updatesdirectory contains updates for the add-on. Read more about how to update the add-on.
readme.htmlfile points to this documentation.
Extract all files in the
public directory of the Zip file to the root of your Business Manager installation.
Log into your Business Manager installation as an admin. You should see the add-on in the main navigation, but before you can use it, you have to go to Settings > Update and click "Run migrations".
Now you can start using the add-on.