Well, that didn't take long. JUST bought a new version, tried to install the com_easyblog_launcher_pro_5.1.13_joomla.zip file on a Joomla 3.6.4 site and can't get pass step 2.
I searched your support, and there are a few entries suggesting this process is "automatic." Not so much, turns out.
This is the message I get with a red button whose only option is to contact support. Here's the message on step 2.
"This package doesn't contain a valid API key and it is most likely downloaded from an unauthorized source. Please do not proceed with the installation as it may tamper with your site."