The login credentials as as follows 
Username :  Mobile Number without the leading zero e.g. 776037743@kenet.ac.ke 
Password:  Use the last six (6) digits of the serial number on the SIM card
For those who might have Eduroam accounts can use them for the above service.

Find attached the User guide for the service.

If you dial the USSD code *544*60# but you see a different menu presentation, it means your mobile number has not be whitelisted/enrolled. You can verify whether your mobile number is whitelisted/enrolled by using the verification page on https://registration.kenet.or.ke/phone_verification_check