Hi please download it here https://marketplace.thingworx.com/Items/google-widgets
To install click on Import/Export on the top of your composer screen (top right), then click on Import Extensions and import the zip file.
Hello seonho Cha,
Please note, that Google Widget isn't a standard and OOTB Thingworx Widget. It's an Extension, that can be found on the Marketplace:
After downloading, just import to Thingworx and refresh the Composer.
Hope it helps.