In Google Tag Manager,

1. Go to your Workspace
2. Click the Overview tab
3. Click Add a new tag and fill in the Tag name, e.g. Conversations.
   

   

4. Click Tag Configuration and choose Custom HTML
   
   

Get the chat widget script from Brevo

Now you need to copy the chat widget script provided by Brevo. You'll find it on the Chat widget settings in Step 3 Install your chat widget.

You can access the Chat widget settings this way:

1. Go to the Conversations tab
2. Click on Settings
3. Go to the Chat widget
4. Complete or skip the Profile and Widget steps before accessing the 3rd step, Install your chat widget

5. Copy the script
   
   

Paste the code in Google Tag Manager

Go back to Google Tag Manager, in the window:

1. Paste the Conversations widget code

2. Click Triggering and choose a trigger (All Pages is a good start)

3. Then click Save in the top right corner

4. Click Submit. 

5. The Submit changes page opens. Add a descriptive name for this change in the Version Name field and click Publish to complete the installation.
   

Now you can see the Conversations widget at the bottom of the page and you are now able to chat directly with your clients.