When the Spaniards planned to conquer China in the 16th Century

[Seiya2000]

a part of an article, which details one of the plans to invade china

"The pressure to proceed with the conquest of China continued unabated throughout the governorships of de Sande’s successors, Gonzalo Ronquillo (1580-83) and Santiago de Vera (1584-90). It culminated with the creation of an even larger and more detailed plan, tabled at a general assembly convened by Governor de Vera in Manila on April 20, 1586. This time the envisioned expeditionary force would be comprised of several hundred Spaniards currently residing in the Philippines, 10,000 or 12,000 reinforcements sent out from Spain, and if possible 5,000 or 6,000 local Indians and an equal number of Japanese recruited by Jesuit missionaries in Japan—between 20,000 and 25,000 men all told. It was additionally suggested that the Portuguese be invited into the enterprise to make the invasion force even more overwhelming, so that its “mere presence and a demonstration will suffice to cause the Chinese to submit, with no great bloodshed.” Otherwise the Chinese, who “are so numerous,…will be deluded and offer resistance; and as the Spaniards are brave fighters, the havoc and slaughter will be infinite, to the great damage of the country.”

[Cristiano viejo]

the biggest problem for Spain would be that they don't have the resources for this undertaking That Spain was unable to spend at the time, the situation is very different from the conquest of the Americas where they just defeated their main and historic rival (the moors), And they had no enemies And they had enough time to organize campaigns in the Americas

This is not entirely true. In the 1500s Spain was in war against French practically the entire century, against the German Protestants and against the Ottomans at the middle of the century, and against the English, the Dutch and the Portuguese at the end of the century.

Another misconception that bothers me Is that part of the Spanish history they teach as If their truly goal was to spread Christianity to the new world, When In reality their goal was to empowered themselves with gold or exploit someone else resources.

At least In regard to "New Spain" case.

Indeed the main goal was spreading the Catholicism.

A very big part of the resources were destined to... the own America. How do you think churches, chatedrals, ports, roads, cities, schools, universities etc were built??