This solved my issue. Maybe it will help somebody. Firstly, I installed React dependencies in my project using "npm install react@latest react-dom@latest". Afterwards, I installed "yarn" with "npm install --global yarn" and then "yarn create react-app client --template typescript". (Following command did not work for me at all: "npx create-react-app client --template typescript".) After the succesfull installation I was able to go into the folder "cd client" and start React by "npm start".