Intricacies of Designated Zone in UAE and it's VAT and Customs Obligations

Hi,

I'd like to seek for clarification on our case, we are a manufacturing company in a designated zone and sold goods in the UAE mainland in DDP terms.  Since it is in DDP, we are obligated to pay the VAT, and we made it in cash.  The import license used was for the enduser (which is the client of our customer).  I assume we need to adjust the amount paid in Box 7 in vat return?  Also, do we need to issue an invoice with 5% tax, or we not required since it would technically be a double cash payment to tax authorities?

Thanking you in advance for your reply.