How to schedule notification with Thunkable pro using one signal?

We have created an app that is some form of a calendar. Now we are trying to add notifications so that it will give you a notification before each event that is in your calendar. We have successfully created a one-signal account and we already have Thunkable pro. We have also been able to send scheduled notifications to our device, but we are not sure how to link it with each event and individual users. Could anyone help us with that?