The first thing you would do is prepare the substrate. Meaning remove any loose crumbly substrate, make sure the substrate is clean, dry, free of any previous applied products, and foreign matter.
Patch and profile any joints, seams, cracks, holes and rough areas using LRB/TAV mixture (Liquid Rubber Base, Thickening Activator). 2-parts LRB is mixed with 1-part TAV. LRB can be used by itself (as a liquid membrane) to smooth out a rough floor. Wall/floor junctions require a 1” diameter bead of LRB/TAV mixture and most cracks use a 3/4" diameter bead. LRB/TAV “Round Caulk Bead Chart”
Topcoat using PermaFlex (240 sq ft per gal). Shown using Light Tan.