Press cmd/ctrl + shift + p to open the command palette.

Type install package and press enter. 

Then search for SyncedSidebarBg

wait installed

next search for ayu

settings Preferences > 

Setting - UserFor light theme:

"theme": "ayu-light.sublime-theme",

"color_scheme": "Packages/ayu/ayu-light.tmTheme",

For mirage theme:

"theme": "ayu-mirage.sublime-theme",

"color_scheme": "Packages/ayu/ayu-mirage.tmTheme",

For dark theme:

"theme": "ayu-dark.sublime-theme",

"color_scheme": "Packages/ayu/ayu-dark.tmTheme"