Steps to reproduce the issue

• On a setup that is misconfigured in some way, click the "Add Install From Web" button on a new installation

Expected result

One of:

• A successful installation

• A message giving sufficient information to fix the issue e.g. :

• Unable to download install package to extensions folder - folder is not writeable by server

• Unable to extract install package to administration/components folder - zip extension is missing

Actual result

Error 
Unable to find install package 

System information (as much as possible)

• Server - Ubuntu 18.04.
• Database: mysql 5.7.27
• PHP: 7.2.19
• Apache - Apache/2.4.29
• Joomla! 3.9.19 Stable

Additional comments

Likely the issue in my individual case is that a certain folder needs chgrp-ing. But this is a not un-reported issue on other installs (e.g. https://stackoverflow.com/questions/47210149/joomla-error-unable-to-find-install-package ) and surely it's possible to do better.

From code inspection this likely affects 3.x and 4.x:

• joomla-cms/administrator/components/com_installer/models/install.php

  Line 181 in 76d4b49

  $app->enqueueMessage(JText::_('COM_INSTALLER_UNABLE_TO_FIND_INSTALL_PACKAGE'), 'error');

• https://github.com/joomla/joomla-cms/blob/4.1-dev/administrator/components/com_installer/src/Model/InstallModel.php#L195