Print summary:

Start with objects in the "recommended" folder.
Print one object at a time, otherwise it doesn’t work at all.

Either use “vase mode”, OR: no infill and no top layers with 2 perimeters and make sure the seam is aligned
It can help to use wider extrusion, thicker layers, and if possible larger nozzle. (I used 0.65mm extrusion. 0.3mm layer height with 0.4mm nozzle, or 0.4mm layer height for 0.6mm nozzle)
Print very slow, at about 20mm/s (for perimeters and external perimeters).
Printing a bit hotter can help.

Use filament with opaque and uniform color, nothing that tends to blend layers and look smooth.