With most bullet based weaponry, you are extremely inaccurate while moving, and are dependant on standing still to maintain maximum accuracy. With regards to game mechanics, there's a few things to keep in mind. It's not perfect, but it helps, and it shouldn't impede your ability to download the Steam client or Fistful of Frags.
This is a countermeasure against scamming accounts, which have a tendency to not have any sort of financial transaction history on those specific accounts. The removal of restrictions includes the addition of funds to your Steam wallet. Keep in mind that your Steam account will have certain features restricted until monetary exchanges cumulate up to $5 on your account. Downloading both items are perfectly safe so long as you don't have any preexisting malware on your system (you have a Mac so I doubt you have any). Should be pretty straightforward and take a bit of time. You first have to download Steam and create a Steam account to be allowed to download Fistful of Frags from Steam. Fistful of Frags is available on Steam, which is a trusted website for digital downloads.
