Linking apps across platforms. IOS to Windows

I bought the pro for version my iPad now I have just purchased the version for Windows 11. How do I link them?

Diarium version: 2.9.29.0
OS + version: Windows 11

Not sure about windows in specific

But we have cloud sync option under settings
We have various options of cloud.
You should choose same cloud in each platform /device

So your data sits on someone else’s server? I thought this was a standalone program?

TeeKay What do you mean with "someone else's sever"? You can choose in the Cloud Sync dropdown what cloud service should be used for storing the data online. You can choose to not use that feature if you don't want to. You can also host a WebDAV server yourself (e.g. Nextcloud) and use that for the Cloud Sync.