Download from here. Unusual for them -- they mention to check back on May 4 so maybe that's when next freebie will be available.
There's also a booklikes bookclub to read these freebies at TOR Monthly free ebook book club.
Publisher page for more info on the book is here. It's also the NPR Best Book of the Year.
So I got hooked on these when TOR had first book free -- bitching the whole way at the cost of the other novellas in the series but still hooked enough to preorder the things.
Now during this pandemic and before the May release of the 5th novella, TOR is making all four free, one each day (I wasn't online to post before now). They are very serious about cutoff times (they don't spam the email you give them).
I am so ready to be back in Murderbot's head when the new book arrives.
Tired of browsing the public domain for free books? I'm not. I recently downloaded an early Rex Stout. But if you're looking for something a bit more contemporary and don't feel like paying for it, try this book of short stories. It's free during the pandemic. Currently it's free on Smashwords. In a few days it will be free from Apple and B&N. Only, please don't let Amazon know it's free or that fat monopoly will unlist it.