I need a system to automate all whatsapp notifications

I have a Shopify store to teach English online, and need to send my customers automated whatsapp messages to confirm their purchases, send them class notifications and reminders , and send them renewal notifications.

The customers numbers and order details are being stored in a google sheet to centralize the orders database since we have purchases by bank transfers as well.

I need a system to automate all whatsapp notifications since it's being sent manually and required lot of time and effort to manage.

Please let me now if you can help

Thank you