1. Copy the .jsx file to the AE script directory: (eg: sWITCH.jsxbin)

Win: ...Adobe After Effects CC\Support Files\Scripts\ScriptUI Panels\
Mac: Applications\Adobe After Effects CC\Scripts\ScriptUI Panels\


2. Open the AE software settings and check *Allow scripts to read, write and access the network

Win: Edit-Preferences-General
Mac: After Effects CC - Preferences - General


3. You can see the copied .jsx script (such as: sWITCH.jsxbin) under the window menu at the top of the software