Or is their a diffrent way to call third part libs?
You can create a custom plugin.
I need a Reader Integration to a document management system (DMS). The user should interact from Reader GUI with the DMS.
Nobody is able to give me binding statement, if my customer (this company need plugin for internal use only) will get the Adobe Reader Integration Key License/digital certificate for such a Reader plugin and how high the costs will be. I wait and wait for Adobes’ Feedback :-(
Sounds more like you need an external application which interacts with the DMS and runs Reader/Acrobat as needed.