To install D++ on a project from XMake:

Ensure XMake is correctly installed
Create a new XMake project if you haven't already one, using xmake create <project_name>
Update the xmake.lua file by adding the dpp package, below the minimum configuration:

add_rules("mode.debug", "mode.release")
 
add_requires("dpp")
 
target("test-bot")
    set_kind("binary")
    add_files("src/*.cpp")
 
    add_packages("dpp")

Finally, run xmake build to download dependencies and build the project