Using Android Studio, the correct repo is at

https://maven.scijava.org/content/repositories/public/com/github/QuadFlask/colorpicker/0.0.15/colorpicker-0.0.15.pom

so this old repo will display 404 error https://dl.google.com/dl/android/maven2/com/github/QuadFlask/colorpicker/0.0.15/colorpicker-0.0.15.pom

nor

https://repo.maven.apache.org/maven2/com/github/QuadFlask/colorpicker/0.0.15/colorpicker-0.0.15.pom

Therefore, it could not find the repo in these two locations.

You fix it by writing in build.gradle(Project level):

buildscript {
    repositories {
        google()
        mavenCentral()
        maven {
            url "https://maven.scijava.org/content/repositories/public/"
            }
    }
    dependencies {
                  .........
    }
}

allprojects {
    repositories {
        google()
        mavenCentral()
        maven {
            url "https://maven.scijava.org/content/repositories/public/"
            }
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

Ensure in the build.gradle(App level):

dependencies 
{        
   ...........
  implementation 'com.github.QuadFlask:colorpicker:0.0.15'
}

Sync project and it will show BUILD SUCCESSFUL.