Why won't the Gleanin advocacy tool appear?

First of all, are you referring to a speaker or an attendee campaign?

For speaker campaigns there is no pop up, just a link to send to speakers. 

If it's an attendee campaign, go to your campaign dashboard for the campaign.

Then click on 'how to run my campaign'
Click 'get my integration code'
On that page, you need to check the box that says 'Display attendee pop up' and select the relevant campaign.

When you do this you will see some javascript appear in the right hand side. You need to copy this code and paste it on to your registration confirmation page.