I’m not exactly sure of the sound I’m looking for, but I want something to fill that silence after a good battle. Something quiet, which allows the PCs to recharge, but compliments that they just survived a battle.
Possibly it’s just wind or ambience, maybe it’s a calming song.
What have people used and what would you all suggest?
Here some musical suggestions.
Search for samples in the library “new Heroes of Phandelver” There should be 10 of them.
You can also use the keywords in the library (if you use the search, this will not work) “calm” and “music” There should be around 50 tracks there. All different. Some synthy, some somber, some light.
For wind an other sounds, there are some elements. “Mountain wind” is good. “Crow forest” if you want an ominous forest. “Forestry grounds” for a brighter woodland.
Hope that gets you started
You might also use search to look for MOODS called Aftermath?
Works? 
Thank you, both. All helpful.
Though, what is the difference between Library and Search?
There are a variety of Aftermath moods, ranging from an aftermath that includes fire and screams and wailing to just simple silence from battle suddenly ended.
Dragon Heist’s Zhentarim Hideout includes a soft aftermath of breeze and creaks indoors, along with a hint of unease (after fighting off guards). But the Fireball set from the same adventure is literally the aftermath of a fireball going off in the middle of a market, and involves crying and wailing and the crackle of flames (with the option of rain). Gralhund Villa (also Dragon Heist) is also soft wind and faint shadow breaths, but in a nice house (no creaking) with a hint of street noise from outside.
Outlaws of Alkenstar - The Smoking Gun - has an aftermath that is slightly sad music, wind, street/city noise, and rain.
Rise of the Runelords has two aftermath moods, one in Attack on Sandpoint, the other in Stones over Sandpoint - both are city life with flames from the aftermath of fiery attacks.
Finally RealmSmith’s - The Desecration of Blackwell has an aftermath that is super creepy - very unsettling music/sounds/heartbeat drums, very much a horror movie sort of sound.
Library searches for specific elements or samples. Search also includes moods, sets, and one-shots. Library would be if you’re looking for a very specific kind of sample or element. Search lets you see every possible thing available.
Really appreciate the detailed reply!