الخلاصة (BLUF): Retopology lightens the mesh: it cuts the face count while keeping quality and bakes the existing textures onto the new geometry.
Triangles or quads. v2.0 is the smart default (30 credits), v3.0 gives cleaner edge flow (35 credits, 40 for quad), v1.0 is plain reduction (10).
Smart UV is supported on v3.0 only; baking works on v3.0 and v2.0.
A GLB with your chosen face limit — stated as a number in the form; typical game budgets are 500–20 000 faces.
Quads cost +5 credits: worth it when the model goes on to Blender-style workflows that prefer quad meshes.
Bake (on by default) re-projects the existing textures onto the new mesh; switch it off if you only need geometry.