To install HappyFox Chat via Google Manager:

Follow the steps here > https://support.happyfoxchat.com/kb/article/429-how-to-install-happyfox-chat-via-google-tag-manager

Steps to hide the installed widget on specific pages via GTM: 

Step 1: Login to your Google Tag Manager -> Go to the tag created to install HappyFox Chat.

Step 2: Click "Triggering" -> Hit "Exception" option.

Step 3: Now Configure the Trigger Exception

i) Click trigger configuration tile to Choose trigger type - Page View.

ii) Under "This trigger fires on", choose - "Some Page views".

iii) Enter the URL details on which the widget should be hidden. 

Step 4:  Now "Save", "Submit" and "Publish".

Widget on "About" page will be shown

Where as per the exception trigger, widget on books page will be hidden.