I have no idea why this problem is happening when I try to clone a GitHub fork. This problem happens with other forks as well.
Try and create one manually.
If you can't (create it manually), that could highlight a permission issue, which would explain why it was not created by Git in the first place.
As the OP zuckonit mention in the comment:
I fixed it: If I disable ransomware protection on my PC, everything is fixed.