By using Zapiet - Pickup + Delivery you can automatically apply a discount code to all of your pickup orders.

Requirements

You will need to have a discount code created in Shopify.
- To add the discount code, you can follow the Shopify YouTube tutorial in their Discounts guide.
You will need to have Prepopulate shipping address fields enabled.
You can enable this in Zapiet - Pickup + Delivery > Settings > Store pickup.

Add the discount code in Zapiet - Pickup + Delivery

Click Settings, then Store pickup.
Find the Discounts section and enter the discount code you created in Shopify.
This field is case-sensitive—“PickUp” is not the same as “pickup”.
You can only add one discount code at a time.
Click Save.

Your pickup discount code should be automatically applied at checkout.

You cannot use this feature if you are using pickup only mode.
Only one pickup discount code can be added at a time.
If a customer uses this discount code, then goes back to the cart and chooses a different checkout method, the discount code will still be applied.
To get around this, you can add a discount code in Shopify for a discount of 0.00, and add this discount code to your shipping and local delivery settings.
As this is a Shopify discount, customers can copy one checkout methods discount code and apply it to another. There is no way to stop the discount code from working if a customer manually adds it in—this is a Shopify limitation.
When using rates with Carrier Service API, our app calculates the pickup rate based on the order total before any discounts have been applied. This is because the post-discount cart total is not available via the Shopify Carrier Service API—it is a Shopify limitation.
- This limitation does not apply to Zapiet - Pickup + Delivery rates.

Check that the pickup code added in Shopify is the exact same as the one added in Zapiet - Pickup + Delivery.
Check that your store is not using pickup only mode.
Check that the discount made in Shopify is a discount code (not automatic discount).
Check if you're using an incompatible app.
If you are using multiple discounts, check which discounts can be combined.
Check that you have enabled Prepopulate shipping address fields.
You can enable this in Zapiet - Pickup + Delivery > Settings > Store pickup.