In the "Payment terms" section, you can set the term by which invoices should be paid. You also have the option of creating reminders (automatic or not). First, navigate to the "Admin" panel.
Next, select "Payment terms".
You will be taken to the "Payment terms" section, where you can manage the terms and associated reminders.
Create a new payment term
To create a new payment term, tap the button "+ Payment Term" at the top right.
On the next screen, fill in the name, the days until due date and the text that has to be written on the invoice. To confirm, select "Save".
Add a reminder to the payment term
At the right side of your screen, you can find all the settings with regards to your reminders.
In this section you can choose, for example, if you want to send automatic reminders or not.
To create a new reminder, select the button "+ Reminder".
On the next screen, fill in the reminder interval, the cost price, the communication channel you prefer and whether or not you want to include the original invoice. You can also indicate if you wish to send the reminders automatically or not. 
You can manage the created reminders under the "Reminders" window. Each reminder can be set to active via the slider shown below. Enter the necessary parameters, such as the number of days before the reminder is sent.
The "Send via" section allows you to choose the way you want to send the reminder. This can be by e-mail, phone or post.