If you are using npm 7 (you can find out the version by typing npm -v in your terminal), then you may get the following error when you run npm install:
npm ERR! Could not resolve dependency:
npm ERR! peer react@"^16.14.0" from react-test-renderer@16.14.0
npm ERR! node_modules/enzyme-adapter-react-16/node_modules/react-test-renderer
npm ERR! react-test-renderer@"^16.0.0-0" from enzyme-adapter-react-16@1.15.5
npm ERR! node_modules/enzyme-adapter-react-16
npm ERR! enzyme-adapter-react-16@"^1.14.0" from flex-plugin-test@4.3.5-beta.0
npm ERR! node_modules/flex-plugin-test
npm ERR! flex-plugin-test@"^4.3.5-beta.0" from flex-plugin-scripts@4.3.5-beta.0
npm ERR! node_modules/flex-plugin-scripts
npm ERR! Fix the upstream dependency conflict, or retry
npm ERR! this command with --force, or --legacy-peer-deps
npm ERR! to accept an incorrect (and potentially broken) dependency resolution.To fix this problem, update your package.json and include the react-test-renderer package and use the exact same version you've used for your react package.