How to enable/see Login feature on the site?

[Stromfeldt]

The default theme, Casper, is not designed for members functionality. See this previous comment of mine:

How subscription works in Ghost 3.0?

I could be wrong here, but it sounds to me like the theme you’re using is Casper, which isn’t a members enabled theme. Ghost just released an open source theme that is set up for members, Lyra. You can read more about Lyra, as well as find a download link for it, on the Requirements docs page.