For better DX strongly recommended to use npm@>=7.
It can be installed via npm i -g npm@7 and also it's built-in in node >=15 package.
Use npm run dev for development. (port is 3000 by default).
See packages/*/package.json script section for build, test, lint, etc.
How to use https://github.com/waves-exchange/provider-web/blob/master/packages/provider-web/README.md