To include Google Tag Manager on your event page:
Go to Settings
Select Integrations
Click Add Tracking Script and / or Add Script (depending on what you want to track)
Paste in your Google Tag Manager javascript tag in the Header Script
Click Save


To include Google Tag Manager on your event page:
Go to Settings
Select Integrations
Click Add Tracking Script and / or Add Script (depending on what you want to track)
Paste in your Google Tag Manager javascript tag in the Header Script
Click Save