Hello Nikola I now presume I am auto logged into the support forum as previous message is showing in the forum. 
Anyway as you are already aware, I have installed the latest version of the extension plugin and when installed no buttons are showing on the front end. When I uninstall the ‘submit and cancel’ buttons return to the front end. When re-installing extension plugin the same thing happens again, no buttons. I have the latest versions of the plugins installed, I created application via PayPal and cannot see any obvious reasons for why there should be no buttons showing on the front end?