In order to install realm, requires as follows, in build.gradle (:app)

apply plugin: 'realm-android'

in build.gradle (:Project level)

buildscript {
    ext.realm_version = '10.15.1'
    repositories {
        google()
        maven { url "https://github.com/realm/realm-java" } // Realm repository
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:8.3.1'
        classpath "io.realm:realm-gradle-plugin:$realm_version"
        classpath "io.realm:realm-gradle-plugin:$realm_version-transformer-api"
        classpath "io.realm:realm-gradle-plugin:10.15.1" // Use the latest version
    }
}