In order for scheduled workflows to trigger in SuiteCRM, you must have cronjobs triggering. It is not just as simple as setting up the cronobs in your CPanel, so unless you’re a real expert, the best solution is to open a free EasyCron.com account and then following the instructions of their enormously helpful SuiteCRM Cron Job Tutorial:
https://www.easycron.com/cron-job-tutorials/how-to-set-up-cron-job-for-suitecrm
This will save you an enormous amount of time.