George,
readingril's comments are all valid, and obviously this is the place to start. TTS can indeed be blocked by the publisher, and it is available outside the US. Library loans aren't available outside the US. [Just noticed you're in NY, so the "outside the US" stuff doesn't matter]
It's not clear if this is the only book you've tried, if so then try another book - borrow something else from the library, or "buy" one of the free books from Amazon - just make sure in the Product Details it says "Text to Speech Enabled". This will help you to check that TTS is working properly and whether it is a problem with the book or a general problem.
If you can't get TTS to work with any book, then let us know and we'll help to step you through the process.
If it's this book only, does your library offer Audio book loans? Obviously an audio book is more trouble to manage, being much larger MP3 files, but conversely it is read by a real person, not a computer, and I find much more enjoyable to read (I listen to audiobooks in the car all the time).
It might be worth contacting the library, and explain your position and ask them why TTS is disabled - they may be able to obtain another version for you.
You could also try to see if you can get hold of the book from another source. TTS may be disabled on the library copy, but may work on another version.