Added 'mysql-connector-java-8.0.28.jar.' This is the connector/j driver that is required to connect to the mysql database. This module needs to be added as a dependency to the SchedulerApp (not the default project) (Go to: File -> Project Structure -> Modules -> SchedulerApp -> Dependencies -> '+' -> Jars or Directories...). The file should be in the lib folder in the root of the project.
Then apply the changes.