Wanli is always a guest in the sad autumn, and he has been sick for hundreds of years and only appears on the stage.
"The sad autumn of thousands of miles is often a guest, and the illness of a hundred years makes the stage alone" means: The author has been an official in other places for a long time, wandering outside all year round, often like this thousands of miles away, sentimentalizing this bleak autumn and being a guest all year round. Living in a foreign country, old and sick, the author climbed to the high platform alone.