If the two commands work okay when run directly at a shell prompt, but then they don't work when you run them from inside a perl script, it's either because you did something wrong in the perl script, or else there's a difference between the interactive shell environment and the environment of the sub-shell that gets run from inside the perl script.

As Utilitarian said, it would help if you show your code, and also show the specific error message(s) or other evidence you have that shows exactly what "not working" really means.

And really, if it's just a matter of making it easier to run two processes in sequence without having to wait, using perl for that is overkill. If you just save the two command lines (or a single conjoined command line as suggested in my first reply) as a plain text file, you can "run" that file as a shell script:

source my_shell_script
[download]

or

. my_shell_script
[download]

(note the line-initial period).