$ cat package.lua 
return {
  ...
  dependencies = {
    ...
    "urzds/date",
  }
}
$ ls deps
date.lua
$ lit install
lit version: 2.2.16
luvi version: v2.4.0
command: install
load config: .../.litconfig
connecting: wss://lit.luvit.io/
fail: [string "bundle:libs/calculate-deps.lua"]:75: No such package: urzds/date
stack traceback:
        [C]: in function 'error'
        [string "bundle:libs/calculate-deps.lua"]:75: in function 'addDep'
        [string "bundle:libs/calculate-deps.lua"]:49: in function 'processDeps'
        [string "bundle:libs/calculate-deps.lua"]:92: in function 'calculateDeps'
        [string "bundle:libs/core.lua"]:513: in function 'installDeps'
        [string "bundle:/commands/install.lua"]:5: in function 'fn'
        [string "bundle:deps/require.lua"]:293: in function 'require'
        [string "bundle:main.lua"]:50: in function <[string "bundle:main.lua"]:38>
        [C]: in function 'xpcall'
        [string "bundle:main.lua"]:38: in function <[string "bundle:main.lua"]:31>

To install your dependencies, simply run lit install and it will grab any missing dependencies from package.lua and install them to deps. This will not touch any existing packages in deps.