Just yesterday Microsoft launched Windows 10 Insider build 14291 which includes a long awaited feature - support for extensions on Microsoft Edge! For now, the browser only supports three extensions from Microsoft and that can be downloaded from Microsoft's Website. Users of Microsoft Edge on pc can expect to see third party extensions later this year as per Microsoft.

In a blog post today, they said:

The Windows Insider build will include three preview extensions: Microsoft Translator, an extension that automatically translates pages in over 50 different languages, a Mouse Gestures extension, and an early preview version of the popular Reddit Enhancement Suite (RES). Later this year customers will find popular extensions from partners like AdBlock, Adblock Plus, Amazon, LastPass, Evernote and more.
For Non Insiders, support for extensions in Microsoft Edge will be included in the Redstone update which is scheduled for June-July time frame of this year.