By default, the extension is installed with a disabled Scheduled Job called "Run SQL Tasks". To enable automatic execution of your tasks, this job should be enabled. The run frequency of the Scheduled Job is the minimum frequency at which tasks can be executed, but individual tasks can set their own schedule (see the next chapter). It is recommended to set the frequency to "always" to allow individual tasks to use the schedule that best fits its needs.
You should check the cron configuration for your web server, since SQL tasks may take a long time to execute, depending on what they do. SQL Tasks could interfere with other cron jobs interacting with the database, such as regular dumps. Make sure that each cron job gets the chance to finish before another one is accessing the database.