If you get the following message while installation of Phoca Gallery: JInstaller: :Install: Cannot find Joomla XML setup file, then it seems like your server has a limitation in that it can only extract or create archives with less files than your OS's file handle limit. Phoca Gallery is large component which includes more files than your server is able to unpack (due to the limitation). In such case, please upload extracted files to your server, to e.g. folder: tmp/phocagallery and use Joomla's Install from Directory feature.
1) Create a folder inside tmp folder in your Joomla! root: tmp/phocagallery (with help of FTP client or some file manager).
2) Extract Phoca Gallery Installation ZIP file on your PC and copy all the files (with help of FTP) to your server, to tmp/phocagallery folder.
3) In your Joomla! administration, navigate to Extensions - Extension Manager - Install. Set the right path in form field: Install Directory (in Install from Directory area). E.g. to /your-path/your-joomla/tmp/phocagallery
4) Click on Install. After installation, don't forget to remove the files in folder tmp/phocagallery (include phocagallery folder).