Error Code 5 is quite self explanatory given the message that comes with it :)
Your Community account is already connected to an app account. You can’t have it connected to more than one account.
So if you recently bought a subscription but it’s not on your account, it means you were not logged in while doing so and it’s now been applied to a blank account.
If you could share the callsign for the account where your subscription is now, we can help in merging the accounts.