As strange as it may seem USCIS has two accounts and this just adds to the confusion. One account is via https://egov.uscis.gov/casestatus/displayLogon.do (this is the same login page you provided), this account does not need an access code.

The other account which can be accessed via: https://myaccount.uscis.dhs.gov (this account needs an access code. After I obtained my access code via tech help desk from USCIS, my DACA renewal application was linked and whenever I login in I don't have to enter in my receipt numbers). I hope this helps.