I downloaded the trial of Carbon Copy Cloner, another question. What are the advantages of this over free file sync?
I have never used
Download FreeFileSync 13.7. FreeFileSync is a free open source data backup software that helps you synchronize files and folders on Windows, Linux and macOS.
freefilesync.org
I believe in going with software that is proven, has a history, gives excellent support, and focuses on the Mac environment, instead of trying to be one app for all platforms. In my opinion, that can leave the developer to neglect or miss some important aspects of the software.
Time Machine may work just fine for you, as one of your backup plans. I have had too many instances of it not backing up when it was supposed to and failing to inform of such, as well as creating unstable backups that it doesn't tell you about until you need the backup, and then it is too late.
How important are your files to you? How important is it for you to be able to speak directly to the developer?
You have plenty of time to try CCC. It verifies each backup made and alerts if there is a problem. I suggest you have another off-site backup plan. Always make backups of your backups. Hard drives fail without warning, get damaged, lost or stolen. You can't and shouldn't rely on just CCC, File Sync, or any other singular program.
There is a reason that TimeMachine, CCC, Arq, and SuperDuper are the most talked about programs on this forum. File Sync is not talked about and hasn't been at any length in the time I have been here, which is almost 10 years.
Forty or Fifty dollars for a backup app may seem like a lot at once. However, the benefits provided far outweigh the consequences of not having reliable backup software.