To add this library to your project, do the following:

repositories {
  maven {
    // Location of the maven that hosts Team Resourceful's jars.
    name = "Resourceful Bees Maven"
    url = "https://nexus.resourcefulbees.com/repository/maven-public/"
  }
}

In an Architectury project, you would implement it like so:

Common

dependencies {
  modImplementation "com.teamresourceful.resourcefulconfig:resourcefulconfig-common-1.21:3.0.1"
}

Fabric

dependencies {
  modImplementation "com.teamresourceful.resourcefulconfig:resourcefulconfig-fabric-1.21:3.0.1"
}

Forge

dependencies {
  modImplementation "com.teamresourceful.resourcefulconfig:resourcefulconfig-forge-1.21:3.0.1"
}

You can either Jar-in-Jar this or depend on it on Curseforge or Modrinth.