Sauron's Temple

[Voralphion]

Sauron being known as Annatar, the 'Lord of Gifts', was after Numenor

What do you mean by after Numenor. Sauron was known as Annatar after Numenor was established, but before its fall. When he was captured by Ar-Pharazon the war of the elves and Sauron had already occured and he had taken the rings of power.
The temple was established in Numenor by Sauron after had become the kings councillor as a way of destroying all favour the Numenoreans had left with the Valar. He told them that Melkor Lord of All would free them from death and make them immortal.