There is a green button on the top right corner. You can download the ZIP file from there. Download the whole zip file. Unzip it. Then, once unzipped, place it into your assets folder within your unity project. Unity will automatically recognize any playmaker actions. They dont need to be in a specific place, but, it helps to keep them in folders for organization.
I noticed you posted on my channel. Sorry I havent had a chance to respond. I have been away (and got the flu) this month. I should be back in action by Nov!
If you need help with any of my actions, etc, people are daily active over in the slack chat group I started:
https://invite-playmaker-slack.herokuapp.com