Does the Anchor Text has to be unique?

[davids]

You should use varying amounts of different anchor texts, switching between keyword phrases you want to rank for, website name, and bare URLs anchors like https://www.site.com, www.site.com, and site.com. You can get an idea of your desired anchor text ratio by analyzing competitors sites who are ranking above you.

I don't understand your reply here. What if the site doesn't have www?!

And also providing naked links isn't wise at all. Yields almost nothing.