Your budget is your four buckets. Set what goes into each one every payday, then add spend targets to the categories you want to keep an eye on.
No spend targets in this bucket yet. Everything you spend from it is still tracked by category on your reports — a target just adds a limit to watch.
Every bucket can take spend targets, savings included — money leaves those accounts too. A target is a soft cap you want to watch, not a limit that blocks anything. What you're saving for is separate: set those up on Money Flow.