Not much I can really think to say about this. Its supposed to be "Watercolor". Just use your normal Pony prompts. I'd recommend leaving the strength at 0.7 or 0.8 and lowering or raising it from there.
I'd also recommend including this tag within the prompt:
watercolor_\(artwork\)You can use the Lora without it, but the style won't be quite right if you leave it out, especially on AutismMix (at least on AutismMixConfetti as its the one I personally use and tested with).