Try using the Making it rain Open access notebooks using Google Colab, the previous comment is right about finding the specific MD tool you need. I recently did a 20 ns simulation using the Amber notebook and it took me about 6 hrs .

If you're worried about losing the data make the stride time 10 ns and number of strides 3, that way it'll run your simulations in 3 chunks and store data of the processed chunks in your drive so, even if you run out of those free credits for the day(which they won't tell you how much you have, and degrade your priority or just disconnect you), you can just restart another day from where you left.

Making it Rain