Thanks for the starting point, here is what I ended up with:
I found an old post by B00MER that mentioned having to add the following line of code into include/check_useraccount.php.
Code:
$smarty->assign("user_membership",$user_account["membership"]);
and then for the actual line that changes directories/files I used:
Code:
<a href={if $user_membership eq "Non-Profit"}"/files/non-profit.pdf"{else}"/files/catalog.pdf"{/if}</a>