Hi,
I will walk through a few steps with you. Some of these are just to help figure out what is wrong, not to fix it right away. So if nothing changes after a step, that is normal. I will keep going until we solve it.
Does it help if you https://aka.ms/minecraftClientWindows download this client and sign in?
If you hit the same error, kindly attach a screenshot.
I look forward to hearing from you to get the results of the troubleshooting.