With Online Store and Advanced Store plans, you can connect your website with other services or tools (email marketing platforms, a CRM system, or your accounting software) via Zapier.
To connect your store with an app, look for that service in Zapier – it supports hundreds of them – and create an automated task (a “zap”) by selecting an event and the desired action that should follow it.
You can find Zapier in the Store manager → Apps → App Market.
