Sync a folder without delete

I have a shared folder in dropbox and I'm worried that the shared person will delete the file that shouldn't be deleted.

So, I want to have a backup copy of the folder with all the files (including the files which gets deleted later). How to do that?

How often do you want to back up? Every time something is changed/added or on a schedule?

It's ok to have the backup once a day. But if there's a set time and at that time my computer is not on then I want to get that backup as soon as the next time I turn on my computer.

You can use the "Current time" attribute to schedule it though it won't "catch up" if it can't execute at that time. Also, check out the sticky article on going into subfolders as you'll need that in addition to whatever rule you have to do the copy itself.