A few months ago Microsoft deprecated a service that Syncovery used to identify a user's OneDrive for Business.
If you are using an older Syncovery version from 2019 or before, you will not be able to choose the "OneDrive for Business" protocol and successfully connect it with your account. You will get the error: ESynDriveCheckErrorException ja = Nil.
The solution is to update to the latest Syncovery 8 or 9, or to use the Graph protocol. Graph is also available in Syncovery 7.
Another way to connect to your OneDrive for Business is to use the Sharepoint protocol, and enter the URL with an additional -my, such as:
contoso-my.sharepoint.com
The "-my" signifies that the user's OneDrive for Business is to be used, rather than a company Sharepoint site.