Manifest merger failed with multiple errors, see logs (PayUMoney integration)

I am trying to integrate PayUMoney payment gateway in my app. The very first line of the integration documentation says to add -

compile 'com.payumoney.sdkui:plug-n-play:1.0.0'

in my app-level build.gradle file dependecies. But as soon as I do this i encounter an error -

Manifest merger failed with multiple errors, see logs also the line -

implementation 'com.android.support:appcompat-v7:26.1.0'

show the following error -

All com.android.support libraries must use the exact same version specification (mixing versions can lead to runtime crashes). Found versions 26.1.0, 23.2.1. Examples include com.android.support:animated-vector-drawable:26.1.0 and com.android.support:cardview-v7:23.2.1 less... (Ctrl+F1) 
There are some combinations of libraries, or tools and libraries, that are incompatible, or can lead to bugs. One such incompatibility is compiling with a version of the Android support libraries that is not the latest version (or in particular, a version lower than your targetSdkVersion.)

Help me resolve this issue.

Below is my build.gradle(Module:app) code -

apply plugin: 'com.android.application'

android {
    compileSdkVersion 26
    defaultConfig {
        applicationId "com.learnturtle.payucheck"
        minSdkVersion 15
        targetSdkVersion 26
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}



dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:26.1.0'
    implementation 'com.android.support.constraint:constraint-layout:1.0.2'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.1'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'

    compile 'com.payumoney.sdkui:plug-n-play:1.0.0'
}

Use the latest dependency

compile 'com.payumoney.sdkui:plug-n-play:1.5.0'

and change minSdkversion

minSdkVersion 20