In case any folks who are on a lemmy instance instead of kbin see this post (Hello new users!), boost is a kbin feature, which is a different type of "software" than lemmy. The main kbin instance is https://kbin.social , which can interact with both Lemmy and Mastodon instances
tl;dr - kbin is different than lemmy. They all talk to each other though. Boost is kbin only