what does "pip install ." mean

[ett-baibai]

When I install package following the file named "readme.md":

the system displays an error like this:

as showing, I'v tried to find out the 'setup.py' or 'pyproject.toml', but none of them was found.
My OS is windows 10 PE and my python version is 3.9 in conda env. I don't know how to solve this problem, then it influences my debugging because there is no package named "searchsorted" as below:

as a greendhand, I hope for some help, thanks!

[ett-baibai]

I think I know why: I download the code by ZIP rather than by 'git clone', so, the files in floder 'torchsearchsorted' were not downloaded.

[wtj-zhong]

I only configured the environment today, and a kind person can tell me a qualified configuration horse, because some python3.6 can no longer be found.