Hi, Is Longitude and Latitude information being necessarily for FME to work?

It mostly depends on the type of data you are working with and what result you are expecting.

FME can handle most types of data, spatial or not.

If you have spatial data and you need spatial results, some kind of geometry/coordinates are necessary in any coordinate system, geographical or projected. You also have available connections to different geocoding services (costs may apply) if you need to convert addresses into coordinates.

If you are working with non-spatial data FME can handle it just fine.