What you can do is:

1. Get the version of your NDK by going to C:\Users\<your_user>\AppData\Local\Android\Sdk\ndk
2. Mention the same version in <project_directory>\android\local.properties file by changingndk.dir value to the version you get in step 1. If ndk.dir is absent, add ndk.dir=<your_version> to the file.
3. Set the version of flutter.ndkVersion to the same version in <flutter_dir>\flutter\packages\flutter_tools\gradle\src\main\groovy\flutter.groovy file.