Nordland ex-Niels Juel, what ship?

[zielschiffe]

Hello buddies, I was wondering what classification did this ship get in the Kriegsmarine? Most sources say it was a kadetschulschiff ( cadet school ship), but some sources also claim she was among the flakschiffe ( like Niobe, Nymphe etc.). So what was she exactly?

Additionally, what's a Fla-schulschiff? Is it a typo for Flak-schulschiff?

Thank you very much!!!