It is a single self-contained file for 64-bit Windows 10 or 11, built on .NET 10, with nothing else to install.
The page offers the file only after the server has verified its signed release manifest, and it shows the version, the size and the SHA-256. The file has no Authenticode signature, so Windows may say that the publisher is unknown: check that the SHA-256 of the file you downloaded matches the one on the page.
Once installed, the app checks for new versions by itself and accepts only updates whose manifest is signed by SyncNow's release identity. A new version is offered with Update now or Later, a mandatory one installs without asking, and Updates, in the sidebar, shows the installed version and gets a green dot when a new one is available. Next, sign in: see How do I sign in, and do I need a password?.