From their README


This is where I am keeping my Alfred 2, Alfred 3, and Alfred 4 workflows. It is best to download the whole repository as a zip and then double-click on the workflow you want to install into your Alfred. The Alfred 2 and Alfred 3 workflows are provided as is and will not be updated or modified. This is due to not having Alfred 2 or Alfred 3 on my system anymore. I am strickly running Alfred 4 and loving it.