Is it obligatory to believe that Allah transcends place and time? And what is meant by that? And what is one's duty towards this belief?

The absolute statement that Allah is free from place and time is incorrect, because no sacred text has been revealed to support it, and it suggests a corrupt meaning.

If a speaker says, "We declare Allah to be free from place," if he means that nothing of His creation encompasses Allah, then this is a correct meaning. But if he means to deny Allah's transcendence above His creation, then this is an invalid meaning.

If a speaker says, "We declare Allah to be free from time," if he means that Allah existed before everything and will exist after everything, then this is a correct meaning. But if he means to deny His active attributes related to His will, such as His 'istiwa' (ascension) and 'nuzul' (descent), then this is an invalid meaning.

A Muslim must adhere to the creed of Ahl al-Sunnah wal-Jama'ah and seek knowledge from reliable sources.