You have not provided sufficient information to positively determine your issue. Most likely, you quite an old version of Manager on your old machine. Then, you downloaded and installed a current version on your new machine. Quite a while ago, Manager changed the structure of its database. For a long time, the necessary conversion software was included in the newer versions. But that was recently removed. Therefore, you will need to update in two stages: first to an older version of Manager that still included the conversion, then to the current version.
You can read the developer’s instructions for the process and find links to the interim version of the software in this thread: