How can I set up and track Google Analytics goals on pages hosted on third party platforms such as Teachable, SamCart, and LeadPages?
This is tough to give a specific answer for your specific needs because each platform will behave differently. The best thing to do is try and install the Google Tag Manager (GTM) container snippet on every page you create on all the platforms you use. This will give you the most flexibility when tracking across platforms.
At the very least, you will want the Google Analytics (GA) base code on all your pages.
Once the code is installed, make sure each pageview is tracked inside your consolidated GA account. Once you are confident each pageview is tracking, setting up goals is as easy as matching your pageview pattern to the goal definition.
But I would focus on getting everything you want to track showing up in Google Analytics first and foremost. And I'd recommend using GTM if you can.
Learn more and enroll in our Google Tag Manager Course.