Write a nix shell script to backup files based on my current windows batch file

I currently have a functioning Windows batch file that I wrote which covers the items below. I am moving away from Windows to Linux/Max and need to convert the script in to shell (would take me a long time to learn and I just need a jump start and someones experience & best practice). Functions;

- FTP some files down from a server
- Create a rolling archive for 60 days of files (dated), purge thereafter
- Create a folder backup archive (dated and password protected) of some other files, again keep 60 days
- Copy some folders to a secondary drive
- Log all the results

I will provide the current batch file with some details redacted, the bat is commented throughout and I can obviously answer anything that is unclear).