Google ads conversion tracking?

Hey I am trying to set up conversion tracking with google ads.
I need to follow the steps below:
1. Install the event snippet on the conversion page. This is the page your customers reach on your website after they’ve completed a conversion – the “Thank you for your order” page, for example.
** 1. Open the HTML for the conversion page.**
** 2. Copy the snippet below and paste it between the head tags ( <head></head> ) of the page, right after the global site tag.**

** 3. Save the changes on your web page.**
However, the issue is there is no page reached by a user on a successful sign up. So where do I put this code?
I am trying to track conversions which are newsletter sign ups in my case.

You can create a welcome page in Ghost, and then paste your tracking snippet in the code injection on that page :)