Order PDF in back-end error with Globals
Since the templates are rendered on the server and not in a regular http request (in the front end templates), the globals are not loaded automatically, into the global twig namespace. 

You can still access your global set and use it as you usually would by setting it to a variable. You can do so like this:

{% set companyInfo = craft.globals.getSetByHandle('companyInfo') %}

You can then do:

{{ companyInfo.fieldNameHere }}