It's still smart enough to be able to tell it's a repo even though it's not a bare repo, but calling the parent folder tcoin.git while it's not a bare repo will make cgit think the repo's name is tcoin.git.
In this case, the guide refers to using bare repos and instructs the reader to add the location as a remote, then push to it, rather than interact with it directly.
Using foo.git as the repo's directory is the usual naming convention for bare repos. However, cgit does not include .git in the URL for repos. All of the repos I control on git.tilde.institute use this naming structure, but .git is omitted by cgit from the HTTP path.
The only way I can think of .git being visible is if foo.git contained another repo, bar.git such that the structure is:
public_repos/foo.git/bar.git
In which case foo.git would not be interpreted as a bare repo but as an intentionally named parent directory and namespaced accordingly by cgit.