One of the most important things for a campaign is to make sure it goes out on time, and a great way to do this is by using Scheduled Messages. However, scheduled and recurring campaigns will fail if there are insufficient credits in your account.
To reduce the likelihood of this happening, you're required to configure and enable Auto Top-Up on your account, so when a scheduled campaign sends with insufficient credits, it'll be automatically topped up to prevent failures and your contacts will get the message on time.
Please contact your Administrator to configure Auto Top-Ups for your accounts to ensure your scheduled messages are sent out on time. You can see how to do that here.