drylok is a latex paint concrete sealer kinda like thick paint. I have used it for making a fake buttress root tree, and most recently, a fake rock. I mix acrylic paint in with it to give it color. It is 100% waterproof, so there is no need to seal it or soak it in anything. Basically plug and play.
If you choose to use quick crete or floor grout, they need to be soaked in either water or vinegar to fully cure it and neutralize the pH. Basically, you soak it in water for a month or so and check the pH frequently until its around 7. Vinegar takes less time because it is an acid and neutralizes the pH more quickly Alternatively, you can use acrylic masonry fortifier to seal the concrete or grout and not worry about soaking it.