Nitro Pro Outlook Add in is not working

[JP Escario 0]

Nitro Pro is showing in the list of Addins but when enabled, it is still not showing up. 

Nitro Pro Version is: 11.0.5.271

See below image:

https://ibb.co/FD95tWt

This is the Microsoft Office Version of the computer:

https://ibb.co/nMFLf5h

I have done the steps provided in this link but still not working: 

Re-installing Nitro addons:
http://kb.gonitro.com/knowledgebase#/search/office addin/000002195

Forcing Nitro addons to be enabled:
http://kb.gonitro.com/knowledgebase#/answers/Nitro Pro/000002273