you may not like the looks but its new,,, just wait a bit til the conc's dirty & aged,,, those spots'll be more difficult to notice.
far's a coating of 'mud' over it, correct mtl's generically call'd polymer-modified cement OR, in other words, CONCRETE,,, our mtl of choice has white cement, several sizes/shapes of silica aggregate, polymers, & water we add as required,,, we can also add uv-resistant color,,, thickness is nominally 1/16" w/compressive strength of 4,500psi,,, we charge $3.50sf incl prep here in atl.
if you etch w/muriatic, there'll still be color variations,,, you could acid-stain it ( i wouldn't ) but there's no paint worth a **** for conc.