1- Your application needs to use some libraries like react, these libraries should be present in the root of your project path in the node_modules folder. After creating your project, you need to run "npm install" on the command line to install all the libraries listed in your project's package.json. After that, if you need to add a new library, you need to install it individually.

2- You need to install node_modules by running "npm install" on the command line (in your project path).