You may use Bridge with an offline license file if you are on an Annual subscription or Unreal Unlimited plan. Your offline license file can be found in your Account page at quixel.com/account. To activate Bridge with an offline license file, simply open Bridge > Edit > Settings > More Settings > Activate with license file.
If you have a working internet without any restrictions like proxy servers, then you will be able to download plugins. If there is restricted internet, please refer to this FAQ.