To travel to Spain if you have an EU DCC, or equivalent EU it is not necessary to complete the SpTH health control form.
On the official homepage you can find more information about the vaccination, recovery or diagnostic test DCCs that are valid for travelling to Spain.
By clicking here: here you can consult the countries that have an EU equivalent certificate.
People in transit and children under the age of 12 do not have to show DCC or SPTH QR.
You will have to show the DCC prior to boarding and when passing the health controls, please follow the indications that you will see upon arrival at the airport.
For more information on the health requirements necessary to pass health controls at the airport of arrival in Spain, please click on this link.