When you select Work without using your Sage account on the Manage cloud connection window, you see the following error:
'Access Denied: You cannot access the Manage cloud connection wizard because (username) is logged in on machine (computer name).'

UPDATED: This issue is resolved in v30.1 and above of Sage 50 Accounts. If you aren't using the latest version upgrade now > If you are unable to upgrade, use the workaround below.
Other users can now log in successfully.

If the Sage account is unavailable temporarily, choose Work without your Sage account. Reconnect when the Manager user is available.
Only 1 user will be able to process until you Reconnect using your Sage account.
If you don't want to use Connected services, or are unable to recover the account used to set them up, follow these steps: