ruditimmermans You need the Extension Manager, which allows you to install any extensions on your forum without SSH access. If you installed the forum by unpacking the archive, it should already be included in the default set of extensions.
Once you have the Extension Manager, type sycho/flarum-private-facade into its search bar, and the extension will appear right away.
If you don’t have the Extension Manager in your extensions list, you need to contact your cloud administrator so they can install it for you using the command: composer require flarum/extension-manager:"*"