Trying to remember what i learned in history here, i hope i get at least most of it right:
- the political institutions of the Weimar republic were not as balanced and protected from interference as in other democracies
- many parties were against the existence of the Weimar Republic
- they differed a little in what they wanted instead though, ranging from reintroducing the monarchy with a few republican elements, to full fledged socialism
- the difference between the parties made finding compromises very difficult and often resulted in stalemates in the legislative, because of missing checks this did not affect the executive as much though
- especially the monarchists liked the idea of heaving a leader that can overrule the parliament if needed and so it was easy for Hitler to get them to agree that they would all be better off with him breaking the stalemate so to speak. So they formed a coalition
- see also https://en.wikipedia.org/wiki/Harzburg_Front
- Those parties also had no qualms with banning other parties just because they disagreed on something, which Hitler was very happy to do, starting with the communists and ending with a complete ban on forming political parties after every serious contender was eliminated
You are technically correct in saying that it’s not a registration. Instead it’s a sponsoring: https://en.wikipedia.org/wiki/Sponsored_top-level_domain