Is it permissible to act upon an existing fatwa that resembles my situation, or must the issue be presented directly to the people of knowledge?

A Muslim must not undertake any action until they know Allah's ruling concerning it. They should ask people of knowledge to verify the ruling on the matter. If a person has the capacity to understand jurisprudential issues and finds a fatwa from a trustworthy scholar, they may act upon it. However, if the matter is unclear to them or if they are unsure about the fatwa, they must ask people of knowledge, as Allah states: ﴿So ask the people of the Reminder if you do not know.﴾