If you are concerned about the visual imperfection of a seam in your rubber flooring, this isn’t your solution as the seam becomes soooo much more apparent. My suggestion there is butt the seam well during installation. It will disappear.
I certainly wouldn’t recommend this sealer for flooring with a color fleck unless you don’t care about covering the flecks and seeing the sealer.
If your need for a sealer is related to a concern about moisture, this is your product. It’’s basically tar. Use disposable rubber gloves!