To be able to add pickup points as an option, you need to have the Shopify CarrierService API enabled. You can do this in the following ways:
If you have an Advanced Shopify plan or higher, the CarrierService API is included in your Shopify, and you don't need to do anything else.
If you pay for your subscription (Basic or Standard Shopify) annually, you can access the API for free.
If you pay for your subscription (Basic or Standard Shopify) on a monthly basis, you can purchase access to the CarrierService API for $20 per month.