??

I think it means that they also wanna read it, but they don't know the manga.

when u comment on a post, u get notifications. so like the person above said, it's usually to find a certain manga

Usually it's when someone describes a manga they don't know the name of, and ask others to help them find it. When you here the description and don't know the title, but still want to read it, you say, "following." Saying things like sorry is because you get the notification and expect an answer, but actually you see that someone else is interested, so you apologize for wasting their time. I hope this helped you understand! ╮(￣▽￣)╭

This feature doesn't applicable to anonymous.

it's when you want to follow a question. Manga-go really should add a "follow" button in this section (●'◡'●)ﾉ