Move the libraries folder to your sketchbook folder. In the end it should look like:

sketchbooks
  - HackerspaceActivityMonitor
    - HackerspaceActivityMonitor.ino

  - libraries
    - DHT
      - DHT.cpp
      - DHT.h
      - ... more stuff

    - ERxPachube
      - ERxPachube.cpp
      - ERxPachube.h
      - ... more stuff

    - ... more libs that you downloaded

  - ... more projects in your sketchbook folder