If you have configured shipping rules in your PayPal profile it may attempt to apply them to digital orders sent through DPD for checkout.
Because of this, you need to set each shipping method configured to allow the shipping charges sent by DPD to override your PayPal shipping calculations.
To set the override:
1. Log in to PayPal
2. Go to the profile menu and select “Profile and Settings"
3. Go to the My Selling Tools tab, then click on “Update” beside Shipping Calculations
4. Select a shipping calculation and click Edit to open that calculation:
5. On the edit page, make sure the “Use the shipping fee in my transaction” option is set to YES, then save.
6. Repeat step 4-5 for every shipping calculation you have configured in PayPal.
Once all methods are set to allow per transactions overrides using the settings above DPD will be able to send 0 shipping orders and DPD shipping calculation orders to PayPal without there being a conflict with your PayPal shipping rules.
Alternately, if you are not using PayPal shipping calculations for other sites or services, you can just delete them.