If your Mac/Safari/iOS device has enabled cookies but is still getting the message "the site needs cookies enabled", You will need to uncheck the "Prevent Cross-site Tracking" box in your browser settings. This will allow you (in addition to unchecking the block all cookies box) to gain access to the site.
To enable cookies in Safari on iOS (iPhone/iPad):
Open the Settings App
Scroll down and select Safari
Under the Privacy & Security section, turn off "Prevent Cross-Site Tracking" and "Block All Cookies"
For Google Chrome on iOS:
Go to the Settings App
Scroll down and select Chrome
Enable "Cross-Website Tracking"