1. Have you turned on the file sharing?
2. Have you turned on the Password protection?
Please check your Advanced Sharing Settings from Network and Sharing Center. To do this please follow below steps.
1. Click on Start, Control Panel and after that Network and Sharing Center.
2. Now click on Change Advanced Sharing Settings.
3. Now please make sure that your File and Printer Sharing is Turned On and your Password Protected Sharing is Turned Off.
If that does not fix the problem for you, then try to check your Group Policy Settings.
1. Please click Start and key in gpedit.msc in your start search box and press Enter.
2. Now Navigate to the below location
Computer Configuration/ Windows Settings/ Security Settings/ Local Policies
3. Here please click on User Rights Assignment.
4. And Double click on Access this computer from the network and make sure that EVERYONE is added to this list.
5. If something is missing then add it by clicking Add User or group and then just type EVERYONE, click on OK and then Apply and OK.