<This computer isn't linked to an account> That was the message in Dropbox, Preferences, Account.
I spent couple days googling and trying to fix it. Turns out, all my old not existing any more OS installations Dropbox was counting as linked devices. I had 7 of them and you are allowed to have only 3. I unlinked 5 old devices—installations and problem was solved.
Hi @zedi; thanks for joining the Community and happy Friday!
It sounds like you were hitting the device limit on a free, Basic account.
As you found out, if you've previously connected more devices than 3 and you'd like to link a new device (or re-link a previously linked device), you must unlink all currently linked devices (down to less than three), and then you can link your new devices (up to 3).
In any case, I'm glad you were able to resolve this and thanks for sharing this information with the rest of our Community.
Let me know if you have anything else to add or ask; I'll be happy to follow up.