Oh! Well, the fact is that the reason for the problem isn't a problem clearly. The Authorize activation was started, properly.
It is best to sign in with the mod manager of your choice first before signing into Nexusmods page. It will open after you sign in with Vortex, if it is like MO2, and when the page Authorize appears for activation is opened, you have only opened to the main activation page at Nexusmods.
If you have only that page open, clicking to close it after you're authorized will close the browser window. DON'T DO IT! NOT YET! Right click on the NEXUSMODS link up near the Top first and open Nexusmods in a New Tab so you have the main mods page readied. SIGN IN on the new tabs link to Nexusmods.
Click back on the tab where the Authorization was successful and close it, leaving you with only the NEXUSMODs page there and you're still signed in and connected to Nexusmods still.
I like to open Nexusmods in a new tab. Then I close the Authorize page which says activation was successful. You can close the Authorize page then. Then I have the other Tab as the opened page, and I can search the mods sections in NEXUSMOds for a mod I would like to download.
Before you ask, Why didn't you just say, or write that?! Unless you want the job of taking care of me I am not explaining my disability to you.