How can I use an ember-cli-addon without ember-cli?

we are migrating an ember project from version 1.9.0 to the current version. We are not using ember-cli, and as the ember guys pointed out, it is not necessary. We used some plugins with version 1.9.0 that are not working in later versions anymore like this stuff

So we want to replace this old plugins with stuff from here (emberAddons.com).

I have no Idea how to get just the css and js files I need to include into my project from these addons. I already have downloaded the the code from ember-cli-selectize and tried to build it with ember, but, as I always expect from "npm & node & only god knows what dependencies here are breaking", I only get errors:

d:\ember-cli-selectize-master>ember build
Arguments to path.join must be strings
TypeError: Arguments to path.join must be strings
    at Object.win32.join (path.js:233:13)
    at AddonDiscovery.<anonymous> (C:\Users\Philipp\AppData\Roaming\npm\node_modules\ember-cli\lib\models\addon-discovery.js:114:24)
    at Array.map (native)
    at AddonDiscovery.discoverFromDependencies (C:\Users\Philipp\AppData\Roaming\npm\node_modules\ember-cli\lib\models\addon-discovery.js:104:68)
    at AddonDiscovery.discoverChildAddons (C:\Users\Philipp\AppData\Roaming\npm\node_modules\ember-cli\lib\models\addon-discovery.js:71:31)
    at Class.Addon.discoverAddons (C:\Users\Philipp\AppData\Roaming\npm\node_modules\ember-cli\lib\models\addon.js:217:40)
    at Class.Addon.initializeAddons (C:\Users\Philipp\AppData\Roaming\npm\node_modules\ember-cli\lib\models\addon.js:230:8)
    at setupRegistryForEachAddon (C:\Users\Philipp\AppData\Roaming\npm\node_modules\ember-cli\node_modules\ember-cli-preprocess-registry\preprocessors.js:18:10)
    at Object.module.exports.setupRegistry (C:\Users\Philipp\AppData\Roaming\npm\node_modules\ember-cli\node_modules\ember-cli-preprocess-registry\preprocessors.js:46:3)
    at Class.Addon (C:\Users\Philipp\AppData\Roaming\npm\node_modules\ember-cli\lib\models\addon.js:105:5)

By the way, we are working with Visual Studio, WebApi and Ember.js.