After unzip SplineBrush.blend it's important to add Asset Library path for convenient usage: Edit > Preferences > File Path

This will help you to use it in every project without appending it manually, just by dragging it from the Asset Library or adding it from “add” pop-up menus (Shift + A)

Asset library catalog with all available NodeGroups and Objects.

Modifiers will be available in the modifiers menu under the Spline Brush catalog: Spline brush Cards, Camera space, UV Layout

Shaders have their own nodes: SB_Info and SB_Refraction Strokes.

Default Cards and Layout Preset

In SplineBrush.blend file there is a default preset - SB_Strokes. Mostly, this setup is enough to start drawing on surfaces:

Appending strokes preset from asset library in new project.

Appending strokes preset from asset library in new project.

After appending SB_Strokes asset from asset library, you will found 2 objects there: Curve with SB_Spline Brush Cards modifier and **UV Layout object with SB_UV Layout modifier

SB_Strokes

Alternatively you can append data from: File > Append > SplineBrush.blend > NodeTree (Modifiers and Shaders) or Objects (SB_Strokes preset objects with basic modifiers and shaders)