Why are the email notifications not being triggered for my subscription plan?

Generally, if your email templates are enabled under your global settings via Configuration then, Email Templates, you will also want to make sure that the ones you want to be sent to your customers are also enabled on the plan level. You can check the email notifications that are enabled on your plans by going to Configuration then, Plans in the user interface. From there, you can click on the plan name and edit plan at the to right-hand side. In the edit view, at the bottom, you will see the available customer emails that can be enabled/disabled on the plan level. If the checkbox is selected the email template is enabled. Once enabled, the notices will be triggered where applicable.