Reporting presence to authorities while on Schengen visa in Germany

I visited Denmark and Germany on a Schengen visa issued by the Danish consulate. My visit to Germany was for six days and I entered from Denmark. This was mentioned in my visa application.

Hotel bookings were provided for my stay in Germany in the visa application. However, upon visiting Germany, I met a friend and stayed at his residence.

After leaving the Schengen area, I noticed that part (d) of Article 23 from 2016/399 in the Schengen Borders Code states this:

The absence of border control at internal borders shall not affect:….

(d) the possibility for a Member State to provide by law for an obligation on third-country nationals to report their presence on its territory pursuant to the provisions of Article 22 of the Convention implementing the Schengen Agreement of 14 June 1985 between the Governments of the States of the Benelux Economic Union, the Federal Republic of Germany and the French Republic on the gradual abolition of checks at their common borders (‘the Schengen Convention’).

Question 1: Was I supposed to report to the German authorities about my stay when I entered from Denmark?

Question 2: In case I was supposed to report, but I did not, what are the consequences? Is there anyway to fix this? (e.g. ex post facto notification of stay?)

Thanks in advance!