@Prateek did you follow the instructions
did you run pnpm install in the root of the volto monorepo?
You should also update your checkout to the latest version from main, there is alpha.41 and your paste says still alpha.39
EDIT:
I have just checked out the volto repo.
pnpm install
pnpm start
and it ran fine.
Try to checkout the repo in another folder, do these steps and if Volto doesn't start paste the result in a gist and add a comment