Maxi dresses are casual floor length usually in a light cottony fabric strapless, halter or spaghetti strap.
This dress is not casual, it's shiny (in the pic to me at least) and has thickish straps. It looks like a dress to be worn at an autumn evening wedding.
If you want to wear a true maxi dress (i.e. cotton, more casual, etc), I think you could for an afternoon wedding.
if it was pretty much any other fabric it would be more of a maxi dress to me. For me satin=gown
It's:
Material: Charmeuse and Poly/Elastane
I think charmeuse is supposed to be some sort of silk knock off. It's a super light material.
When I think of satin, I think of a heavy prom/wedding gown material.
charmeuse is a satin weave. It's a lighter weight but still satin. If it's hot where you are you may want to reconsider. The "poly" indicates that it is synthetic and that means it's not going to breathe well at all.
It's really hard to get a sense of how the black dress looks from that picture, but if you're not comfortable in it, you shouldn't wear it. Personally, I don't think I would be comfortable in the other dress either, b/c I do think it is a bit showy and too much white.
But it seems like it is not too flashy for your circle and it seems like you will be much more comfortable in it. So if you don't have time to shop for another dress, than I guess I would just go for it.