Notifications do not come, despite the fact that I put a checkbox "Notify me..."

[User2]

I created a topic on this forum and put a checkbox "Notify me of new answers in this topic". But the notifications did not come to the mail. My mail does not block spam.
Today I went into my topic to check just in case, and I see what was answered in my topic.
Then I look above the topic, above the topic it is indicated that I am not subscribed.

It's the same with this theme.

[m4z]

Did you check under ${your profile} -> "Notifications" (not sure if this direct link will work) if emails are enabled instead of just (in-browser) alerts?

You're referring to another theme. The phrasing of that option you quoted suggests to me the theme might not be compatible with 2.1 RC4 because it doesn't distinguish between mails and alerts. This might also be the cause of the "Notify me [for this topic]" not working (if you posted using the other theme).
If you change the "not subscribed" while using the default theme, is the change being saved successfully?

[User2]

m4z, I didn't have notifications configured in my profile. Now I have set up notifications and will see if notifications will come.

[User2]

Yes, the notifications are working.