Have you aleready watched the tutorial from Derek Ross? Things for a lot clearer for me afterwards.

And I often do not do it too: but actually reading the documentation really helps, also for mkstack. And if you follow all the steps it gets really simple.

From my beginner experience I would recommend trying a llm via provider such as payperq or openrouter in the beginning. Then play around with deepseek and other free models. And I you have a clear idea, give Claude sonnet a shot.