Independent of which platform you are planning to use, there are some configuration parameters you should consider changing before setting up H5P. These parameters are related to file upload, and the max sizes allowed by your web server.
Start by finding the php.ini in use by your web server, and open it in any text editor. When deciding how large files you will allow being uploaded, have in mind these settings is relevant both when uploading H5P-files, and when uploading other files to your site. The parameters you would like to change, are upload_max_filesize and post_max_size. In the example below, these values are set to 128MB. Note that post_max_size should always be larger or equal to upload_max_filesize.
If you set upload_max_filesize to 64M and post_max_size to 128M, this means that you can upload two files at max 64M at the same time. (in the same request)
; Maximum allowed size for uploaded files. upload_max_filesize = 128M ; Maximum size of POST data that PHP will accept. post_max_size = 128M
After saving the changes to php.ini, you will need to restart your web server so that it reloads the new php.ini.
Now before you go wild with these settings you should keep in mind that increasing them will make you more vulnerable to vicious Denial of Service attacks, as your server will spend more time handling requests. As of PHP 5.3.1 there's a setting called max_file_uploads that will limit the number of simultaneous uploads for all users.
If you're still having issues uploading big files after you've changed these settings, you should check your web server for a max request size limit. In nginx this will be called client_max_body_size.