For your first project using CFD I suggest first to learn how to correctly simulate an aircraft wing. You can find some good examples in project space of SimScale. It could take few weeks minimum. You will feel at easy after few months.
Your current project with 20 degree tiny spoiler is very difficult due to shape of the spoiler (3 mm thick), emboss on the wing left by the open spoiler, span of the wing (~1.2 m) compared to the spoiler. Difficulty comes already from meshing, as you will have enormous ‘aspect ratio’ of mesh cells (ratio of smallest mesh cell to biggest cells).
As a result, creating right mesh will consume your core-hours quickly…
My advice would be to use ‘quasi-2D’ approach and not start with full 3D simulation. In that case, you take a wing ‘section’ of, say, 5 o 10 cm only, having that spoiler in. Meshing and first simulation results will be quick, comparing different angles would be possible, you will not exhaust your core-hours in couple of weeks.
However @DaleKramer or @dschroeder can give better advice.