Whenever you migrate an account to a Jagex Account,
the previous login details become useless/obsolete
. You will not be able to use them ever again.
You ought to use the NEW email address and password that you had just created when the Jagex Account was formed
. Once that's done, it's also recommended to completely log out of the Jagex Launcher to ensure that the system picks up the transfer.
If it's the second, then you need to sign out of all accounts on the launcher to get prompted with the correct login. If standalone accounts are signed in, it'll load up the old portal (which cannot access jagex accounts).
It uses the same login portal as you'd access on the website, so as long as the correct one is shown, it'll work.
Can I turn in a paper without citing all sources?
"No."[1]
1. William Shakespeare,
Hamlet
, Act III, Scene 1, line 96.