To unlock the From Rags to Riches trophy in FIFA 19, you will need to complete one of the five available weekly objectives in Ultimate Team.
The weekly objectives refresh every week on a Thursday (I think) and will vary in difficulty. Some are quite simple such as play X number of matches/win X number of matches.
You can find the weekly rewards objectives by loading Ultimate Team > FUT Central >Daily Objectives >
to Weekly Objectives
Complete any of the weekly objectives and the trophy will unlock.