did people worry and write about him being an authoritarian?

Short answer, no.

Hitler's rise was marked--broadly--by a surprising passivity on the part of people who should have known better. Writing criticizing Hitler in the early years tended towards a timid "oh, those Nazis have some good ideas, but they really should restrain themselves a little more..." which barely qualifies as "opposition."

Remember, Hitler was convincing. It's kind of hard for modern Americans to see the appeal (I hope, but now I have some doubts), but the man knew his audience and, in their ears, he made a lot of sense. Life in post-WWI Germany did suck. Everyone was demoralized and humiliated by the German loss. The economy was a disaster. The government was weak, indecisive and, [technically](https://en.wikipedia.org/wiki/Article_48_(Weimar_Constitution) already a dictatorship.

When Hitler roared onto the scene with his assurances of greatness, most people liked what they were hearing, at least enough to "give him a chance." It's important to stress this point. Hitler was charming and stirring personality. He genuinely inspired people. People who heard him speak, even foreigners, walked away surprised by how convincing his arguments were.

After countless Downfall memes, we tend think of him as a sweaty cartoon, but in 1933 Hitler was charming and vigorous and persuasive, while, in a strange way, he wasn't a particularly polarizing figure in Germany. Rather his behavior and personality were polarizing, but his ideas, broadly, were not. He didn't invent antisemitism or the "stab in the back," he merely capitalized on the popularity of ideas already circulating in the public mind.

Remember, this is back when he's promising "to make Germany great again" but before hundreds of thousands of young German men were freezing to death on the Eastern Front.

Meanwhile, despite his charm and obvious ambition, "the people in charge" initially saw Hitler as a temporary aberration, an accident who would soon be removed from power by his own ineptitude and so they didn't take him seriously. Of course, they themselves had no particular vision for what they wanted Germany to be.

People flock to the man with a plan, even if that plan is stupid and genocidal.

After the Nazis came to power, there was loads of resistance to Hitler, but it was unfocused and undocumented, as by then the Party was eager to murder anyone who might criticize the regime. Left-leaning college professors were fired soon after Hitler took power. The press was subverted. Populist messages, no matter how demented, were shouted so loudly that no one could get in a word crosswise. By the time the "intellectuals" (or anyone else) came to the conclusion that Hitler was genuinely dangerous, it was too late to stop him.