SPAIN
This is a useful Spanish Government site which up-dates on COVID regulations and obligations.
Travellers are requested to upload their COVID certificates and enter their data
Ministerio de Sanidad - Professionals - Travel and COVID-19
Also the Melia has own policies. Here is thr information to be found on their website.
https://www.melia.com/covid-19/covid_en.html
https://www.melia.com/covid-19/campaign/generic/docs/Stay_Safe_with_Melia%CC%81.pdf