Don't try to install it manually: your package manager does it automatically. However, a different version of webpack was detected higher up in the tree: code example
Example: If you would prefer to ignore this check, add SKIP_PREFLIGHT_CHECK=true to an .env file in your project. That will permanently disable this message but you might encounter other issues.
// first run in terminal:
yarn add --dev dotenv
// create .env file in root directory
// then add below line in the .env file
SKIP_PREFLIGHT_CHECK=true