Synths are made to be shared both within the Synth platform and externally.
Once you create your Synth, you have 3 initial options. Share to Explore, a Podcast that you have joined as a participant or close (which saves your Synth to your Library).
Once you have selected one of those options, you can share your Synth outside the platform in even more ways. To do that, just open the three dots menu on your Synth to access more options.