Yes, there is an audio version of the book online. You can use it to help you understand the story. Since the book was written quite a while ago, you might find the Victorian language hard to understand. Here are some tips to help you better “get it” for this book.
1. Read enotes summaries. I have given you the first one in a link below. Read each summary alongside the book. If you better know what the characters are and what will happen, it will be easier for you to understand.
2. Read other enotes help pages. Read the section on “style” to help you understand how Stevenson uses words. Since the language is somehow old fashioned, being prepared is the best strategy. For example, Stevenson uses a lot of figurative language.
His friends were those of his own blood, or those whom he had known the longest; his affections, like ivy, were the growth of time, they implied no aptness in the object. (ch 1)
This is an example of a simile, where Stevenson compares his friendships to plants.
3. Listen to an audiobook. Sometimes with old fashioned language, it is easier to understand if someone reads it to you. This YouTube video is excellent to get your started.