Fastpatch/Dashpatch came out uneven...need suggestions?
VCT adhesive isn't going to fill anything or make any corrections. In fact, if you get it too thick your life as you know it will be over.
I'm not familiar with Dash Patch but unless you know what you are doing you stand little chance of flattening that floor with just any cheap patching compound and a trowel. As Mike has said; the materiel needs to be a Portland based compound.