my Accounting Manager sits on my iCloud Account. My HDD on Mac crashed, and I have just setup my new Mac. However, when I click on the Manager Icon, I get the following

19.2.62: System.Net.Sockets.SocketException (0x80004005): Address already in use
at System.Net.Sockets.Socket.Bind (System.Net.EndPoint localEP) [0x00043] in :0
at System.Net.EndPointListener…ctor (System.Net.HttpListener listener, System.Net.IPAddress addr, System.Int32 port, System.Boolean secure) [0x00047] in :0
at System.Net.EndPointManager.GetEPListener (System.String host, System.Int32 port, System.Net.HttpListener listener, System.Boolean secure) [0x0009d] in :0
at System.Net.EndPointManager.AddPrefixInternal (System.String p, System.Net.HttpListener listener) [0x0005e] in :0
at System.Net.EndPointManager.AddListener (System.Net.HttpListener listener) [0x0009c] in :0
at System.Net.HttpListener.Start () [0x0000f] in :0
at HttpFramework.HttpServer.Start (HttpFramework.HttpApplication httpApplication, System.Nullable`1[T] port, System.String hostname) [0x000e9] in <0c62e0bfd5034c5daf5b80c145468492>:0
at ManagerDesktop.Program.Main (System.String args) [0x0021b] in <95b68200971f45f090b20e8a1b6f9bab>:0

It looks like you have tried to open an old version of Manager, perhaps transferred from a backup when setting up the new machine. That version is thousands of versions behind. Besides, you access your cloud account with a browser, not by opening a locally installed application.

so how do I import my database from the old version into the new version of the software?

There are already several threads about this on the form and the FAQ/Forum Rules indicate that you should first search the forum and read the Guides before starting a posting a question.

In this case one of the relevant threads containing an answer is this one.