Boy, I didn't follow what you said to do. I would how when I was asked to login to my about to activate it there should be no issue.
I think you mixed up your words.
Do you have a roku account... You are here so I assume you do .
1. Login to roku.com and enter your password if asked.
2. Click on the icon on the top left, with the picture of person, and then "My Account"
3 On the bottom of the page click on Link a device in Purple. Be sure you device is on your home network. I think your new device will show a code on the TV enter it . In a few minutes all the apps from the old roku will also be on the new roku (but they may be in a different order).