Is data on 2 PCs mirrored and automatically updated?

I want to have a static PC at home and a laptop on the go. Is there a way to make a certain folder accessible to both through a kind of cloud? It would be important that it is accessible on both PCs even without the Internet and that it is always synchronized quickly or automatically.

Do you have any ideas for me?

Drop box?

Do I not have to have an internet connection if I want to access the data from PC1 or is this saved permanently on the PC?

It also costs min. 10 euro per month. Are there cheaper alternatives?

Quote: "Through offline synchronization and offline access, you can still access the content of your Dropbox,"…

And 2GB are free - but 2G is nothing. You're right.

As an alternative, jz comes to mind only git - but that is difficult to understand and made for other things than just synchronization.

Vltt google again after "offline synchronization cloud" or something.