Before starting, go to your Libsyn dashboard. Navigate to Content—>Prevously Published. Now click the Link/Embed button for the episode.
Below is an Audio block with the Llibsyn direct download link copied as an “External file”. External meaning that it is coming from a source other than Squarespace.
Here is an Embed block with the Libsyn permalink copied into the embed URL section for the block.
Finally, if you want to use the Libsyn custom player, scroll to the Embed section of the Libsyn Link/Embed page, Select the type of player you want and click the “Preview/Get Embed Code” button. Copy and paste this code into a Squarespace Code block.
Below is the Legacy Player using the code from libsyn copied into a Code block.