IIS access requires username and password

1. Open IIS, right click on the website--->Properties--->Directory Security--->Allow anonymous access

2. Right click on the folder of the website--->Security--->Add IUser_XXXX--->Full Control

----------------------- If it still doesn't work--------------------

3. Computer--->Administration--->User--->IUser_XXX reset password

4. IIS--->Anonymous access--->Re-enter username and new password