Beep boop, I’m a bot! I dug through the forum to get you started. I sometimes get things wrong though, so do with this what you will until a human has a look.
Which plugins do you have installed, and is WooCommerce one of them? Action Scheduler isn’t part of WordPress itself. Some plugins bundle it for background tasks, WooCommerce being the best-known. That’s probably why you see the message even though you haven’t scheduled any posts.
A topic with the same message says Action Scheduler relies on WP-Cron:
That topic’s problem may or may not be the same as yours. A related one had the same message together with a “problem spawning a call to the WP-Cron system” error, caused by a 403 when the site called wp-cron.php:
So, to tell which case yours is: does WordPress under Tools → Site Health show a WP-Cron error, such as “Unexpected HTTP response code”? If so, please quote it exactly.
Our knowledge base also says InfinityFree doesn’t provide cron jobs or any other way to run scheduled tasks. The article is about Laravel, but the limit is general.