Notifications on Slash are highly configurable. Notifications are a "Personal setting" not an "Entity setting". This means means different members under the same entity (eg the account owner and an accountant) can configure their own notifications.
Accessing the notifications page
Click the hamburger menu at the bottom left of the dashboard
Click on "Personal settings"
Click on "Notifications"
Changing notification preferences
Use the checkboxes under "email" and "push" to control which notifications you get to your email and which you get to your iPhone (you'll have to download the Slash mobile app to get push notifications)
Setting up Discord notifications
If you'd like to get Slash notifications in Discord, you can set up Webhook notifications.
Steps:
In the Discord server of your choosing, click on the gear icon next to the channel you'd like to get your notifications in
Click on "Integrations" > "Webhooks" > "New Webhook"
Open the newly created webhook and click "Copy Webhook URL"
Go back to Slash, then click the "Webhooks" tab to the right of "Notifications"
Click "Create Webhook", and give your webhook a label, typically this is the channel name where the notifications will go to
Then go back to your notification preferences, and point the desired notification types to the webhook you just created.
Now, the webhook will send a notification to your desired server.
You can add as many webhook URLs as you want