Once Stripe is ready and PayPack is installed, you need to provide your Stripe credentials to the PayPack configuration page in NetSuite.
If you are using PayPack for payment processing, the same Stripe credentials can be used for Stripe Tax.
See this help article to Insert Stripe Credentials into NetSuite.
To enable Stripe Tax, navigate to PayPack > Setup > Configuration.
Under the Tax configuration tab, simply check the box to Enable Tax and click save.