In the attempt to install Crayfish plugin from QGIS Plugin Repository, I often encounter such problem as "Crayfish depends on a platform specifi complied library which was not found. Would you like to automatically download and install one from the developer's website?" By clicking on Yes, a window with a message "Download and installation successful" will be seen. But by clicking "Ok", another message saying "couldn't load plugin crayfish due to error when calling its initGui() method" would be displayed.
Crayfish seems to refer to specific versions of librairies (.so.x) rather than to the main ones (.so), and therefore creates the error you have when loading since it cannot find the library.
Creating symlinks to the main libraries (itself a symlink to the current version of the library) for all libraries in question enables you to start the plugin. I cannot test if the plugin works since I have no files for it.
On (manjaro) linux you can use:
sudo ln -s libproj.so libproj.so.0 sudo ln -s libgdal.so libgdal.so.1 sudo ln -s libnetcdf.so libnetcdf.so.7 sudo ln -s libhdf5.so libhdf5.so.7
in your /lib folder.
According to the developper's website:
If you have problems downloading the binary files, it is likely caused by your proxy server. You can download the files manually and place them under your plugin folder. Make sure you choose the right binaries for your platform. For DLL files you can click here and for ffmpge click here to download the zip files from our server.
You should report this bug to get it fixed (if possible) upstream.