If you are unable to open document library in Explorer view follow these steps:
(your client does not support opening this list with windows explorer)
- Add your site as a trusted site list in your Browser tools option
- Start Internet Explorer.
- On the Tools menu, click Internet Options, and then click the Security tab.
- Click Trusted sites, and then click Sites.
- In the Trusted sites dialog box, type the URL (http://servername:port) of your site in the Add this website to the zone box, and then click Add.
- Click Close, and then click OK.
- Make sure the Web client service is Started.
- If your are using the server as a client then install Desktop Experience Feature (from Server Manager add the feature and then re-boot)