If your system date/time is wrong, activation validation (which uses timestamps) fails.
Aquí tienes un artículo detallado, optimizado para resolver este problema técnico de forma clara y directa. office activado pide activaci%C3%B3n
Alternatively, use the (search for “Microsoft Office uninstall support tool”). If your system date/time is wrong, activation validation
Open Command Prompt as (search cmd , right-click > Run as Administrator). If your system date/time is wrong