How smooth does the floor need to be to lay vinyl plank over it?
You can download the DIY installation instructions here, which contain a lot of guidance on the subfloor requirements, as well as instructions.  They say concrete is a suitable subfloor, although they are probably referring to a typical interior floor rather than a broom finished surface.  

There are also several caveats for concrete.  It needs to be level (i.e., smooth/flat) to within 3/16" per 10 foot radius, and not have a moisture problem (the planks won't be damaged, but the moisture can collect under them and wick to walls and cause damage).  

Ceramic tile (with grout lines), and textured vinyl are suitable subfloors, so the the surface irregularities in those surfaces aren't considered a problem (but they provide more support surface, that is less pointy).  

The planks are rigid, so irregularities won't telegraph through them.  They have a cork bottom layer which should conform to the small points in the surface.  The planks don't expand or contract, which would mean that they don't move in relation to the rough surface, which might abrade the bottom, although they still want you to leave an expansion gap around the perimeter, so who knows.

If you are concerned that the surface is rougher and more irregular than a typical concrete floor, the best bet is to ask them directly.  They have a toll-free support number, 844-743-7439, that you can call to get their recommendation.