You don't "just" protest these kind of authoritarian regimes; there's tons of examples for this.

In Nazi-occupied Netherlands there was a large general strike to oppose the Jewish deportations ("February strike"). This worked out about as well as one would imagine. It was stopped in about a day by force, with several casualties. Most of the organizers were summarily executed days later without much of a trail, dozens others were sent to prison for a decade, and the Germans warned "we let you off easy this time, but next time the consequences will be serious". So that was the end of that kind of protest for the rest of the war.

There's an old Iraqi joke from the 90s (controversy surrounding Bush's Iraq war notwithstanding, it genuinely was an authoritarian regime and atrocious by any standard): "Congratulations mister President, 99.98% of the people voted for you in the election! Only 0.02% of the people voted against you; a fantastic result! What more could you want? The President growls: "their names". It's pretty funny, and also describes the kind of fears people have. Often these fears are very realistic.

Lots of things you and I can "just" do in free democracies just don't apply to authoritarian regimes. I never lived in those kind of circumstances, and I think it takes some amount of effort to really understand what it's like.