It used to be that projects and samples were all saved in iCloud. The folder structure looked like iCloud/Auxy/Samples (it’s actually still there now). You could have a project on like, an iPhone, even with samples, and if you picked up an iPad signed into the same iCloud account you could open that project and all the samples with no issues because they all pointed to the same place.
The change to locally stored samples came in version 6 I think? Or some 5.x release. So what happens now is that both projects and samples are stored locally. If you pick up another device all of the projects and samples no longer live in the cloud, so in order to continue on another device you’d have to airdrop or copy to Files app, etc.
That’s what crystldawn and ThoughtfulNoise are talking about