Google Ads - Set up conversion tracking in Google Ads & Analytics with Tag Manager

Job ID: 33979269

Budget: $30 – $250 USD

I'm running a website at www.bar1672.nl, which has a third party reservation widget on it.
We would like to set up, for Google Ads, conversion tracking. When someone makes a definitive reservation, they click a button and we would like to track that conversion in Google Ads ánd Google Analytics.

The reservation widget is called Resengo, which has a support page on this subject here (in Dutch): https://www.resengo.com/Code/FAQ/FAQ_TextView.asp?DBSUID=13f8ec61%2D6a55%2D4b26%2Db9a9%2Db4f0b1a5552f&CID=0&SF=1&MCID=2&SCID=0&AID=0&FAQID=b2%2BEdQ%3D%3D

Yet, we can't figure this out completely with this guide. We already have a Google Tag manager account for the site.
Related categories: PHP JavaScript Website Design Google Analytics HTML