RR is Royal Road which is another web novel site similar to Scribblehub although the reader base and rules are slightly different there. Most notably, RR has much more restrictive rules on 18+ content while Scribblehub is much more allowing. Lots of authors on RR end up going the Kindle unlimited route and "stub" their works online to meet their contract requirements.
Kindle contracts only allow authors to post something like 10-50 chapters (depending on word count I believe) online for free while the majority of the book is only available on Kindle. So what authors do is write 200+ chapters, gather it into a volume, publish it on Kindle unlimited as an ebook, "stub" their work online. The first 10 chapters that are online for free continue to attract readers and readers that are invested go onto Kindle to read the rest (which makes the author money). Meanwhile, the author keeps writing chapter 201 and more and since they chapters haven't been published to Kindle yet, they can remain online for free, until the author stubs the book again when they want to publish volume 2.
You can look up how authors on Kindle get paid but it's essentially tied to how many pages of your books are read each month.
I don't believe it's very common for web novels posted on Scribblehub, royal road, or other websites to be officially published by a publishing house with a physical book but I know it has happened before.