To install Survicate on your website using Google Tag Manager, follow the guide below:
1. Log into your Google Tag Manager account
2. Make sure you have installed the GTM Tracking Code on your website
3. Click on the Tags -> New -> Tag Configuration
4. Search for Survicate Widget and apply it
5. Go to Survicate -> Settings -> Tracking Code
6. Copy your Workspace Key
7. Paste the key into Instalation Code field in GTM
8. Click on Triggering and select "All Pages" (recommended for basic users).
9. Save and Submit!
The rest of targeting is made via Survicate panel in "Settings" tab of a survey.
More on that here.