Question: how to install zxp manually?
Answer: rename your .zxp file to .zip.
unzip the zip file.
drag that unzipped folder into the folder. C:\Program Files (x86)\Common Files\Adobe\CEP\extensions\
Create a registry entry "PlayerDebugMode" with String value 1 in. HKEY_CURRENT_USER/Software/Adobe/CSXS.5.