I would strongly recommend getting used to sbt. While other tools can be used, it’s the 800-pound gorilla – by far the most common build tool, and the best-supported. (Maven is actually quite important, but most folks use it under the hood – it’s essentially built into sbt for dependency resolution. sbt has a specific syntax for resolving libraries by Maven coordinates.) While it’s not strictly necessary, sbt gets increasingly essential as your application gets complex.
There is a counter-argument that sbt is over-complex, and there’s a lot of ferment in this space, with folks coming up with newer build systems such as cbt and Mill. Those are fun to explore, but not yet something I’d recommend to a beginner.
There are some folks who use Gradle, but most of the ones I’ve spoken with who have used both came out preferring sbt.
So pretty much regardless of what IDE you use, I strongly recommend using sbt on the command line for doing your actual builds.
I’m fond of it – it’s what I use day-to-day – but you should be aware that it’s a bit under-maintained at this point, and tends to be a little glitchy. It’s actually not very common among Scala engineers.
(There’s also a project named ENSIME, for folks who like Emacs, vim, Sublime and other editors. But it’s complex, not really aimed at beginners to the ecosystem.)
By far the most commonly-used IDE is IntelliJ IDEA plus the Scala plugin. While no firm numbers exist, I believe it’s used by a comfortable majority of the community. It has its own issues, mainly when you get into the more sophisticated ends of the language, but there seems a pretty good consensus that it’s the best IDE for beginners. (Note that, while the Ultimate Edition costs money, the Community Edition can be downloaded and used for free, and includes most of the really important features.)
Note also that there’s a bunch of recent movement in this area; it looks likely that there will be more good IDE options available in a year’s time. But for now, I’d recommend IDEA to start out with.