If your budget is zero, do not risk viruses. Use these free brushes that mimic Marc’s style:
I searched the usual places: YouTube comments, Reddit threads (r/ArtResources, r/DigitalPainting), Pinterest, and even DeviantArt groups. Here is the truth: marc brunet advanced brushes free link
Download the files and import them into your software (PS, CSP, or Procreate). If your budget is zero, do not risk viruses
If you are looking to get a in your digital art, I can suggest which brush to use for your specific art style. Just tell me what you're drawing! If your budget is zero