I do not know these lenses in detail, but it seems they have only one "adjustment ring" for the magnification factor. So I read the specification as e.g. a work distance of 210-1000mm with magnification ratios between 0.7x-5x, depending of the set distance.
In other words, if you fix the lens over your table, you *probably* only have one magnification available. Usually a large working distance means low magnification, so in case of the upper lens, you could only work with the 0.7x magnification.
Though the magnification is little, you will have a very shallow depth of field. From my experience this will not be a usable microscope.
Anyhow, the chinese lenses are really cheap and often not to bad. If you´re not to hurt by their price, I´d order one and try. The issues with depth of field will be even worse with more expensive lenses that usually have a larger opening - so if you find out the depth of field is not usable, you know it won't get any better by spending more money.
(And just for completeness: Yes, more expensive lenses may have a variable aperture that can help with the depth of field issue. But as it is always with optics and life in general: It consists of compromises - if you close the aperture so far that you get an acceptable depth of field over the distance, you loose so much light that a usual lab illumination is far to dark. If you close the aperture even further, you get into the diffraction limit and loose not only brightness but also sharpness.)
I would try to find a flexible solution where you can stow away the camera if not used, but are flexible enough to bring it into the optimal working distance if needed...
PS: If you need more experience, ask any macro photographer. The bee that you can easily image with your smartphone - because you are near the object and have a wide depth of field (DOF) - will be much harder to catch with a tele-macro-lens that allows a large working distance. And photographers can spend a lot of time just adjusting the lens, while a microscope should be always and easily available...