How can I print a text field's database value with devel so that it displays on all nodes?
Based on node.tpl.php, it says 


  $node: Full node object. Contains data that may not be safe.


Things I noticed that's not quite right:


dpm() doesnt need to be used with print
dpm($node['content']['system_main']['nodes'][7533]['field_download_link']['#field_nam‌​e']); wouldn't work since $node is an object.


Things to try:


Use only dpm($node); and see what's the output. If the field you're looking for exists then you can continue with manipulating its data
you could place the structuring of your link in hook_preproess_node() and just render it into your template file.