How to synchronize a folder on two PCs?

Question

Data synchronization

Here is such a thing, I have two PCs and the same folder is stored on both, so it is necessary that when it changes on one PC, it changes on the other with the replacement of files. I think that this can be done through the synchronization program with the cloud, but I do not quite understand how.
IMPORTANT!!! PCs ARE NOT IN THE LOCAL NETWORK AND NOT ON AT THE SAME TIME

Answer 1

dropbox, yandex.disk, google drive. You put the client on both computers, you log in from one account, or from two, but you rummage access.

Answer 2

Allway Sync