Perhaps you are unable to connect your site directly to the ConcreteCMS marketplace to install an addon or theme. This manual install or update process works for all addons and themes - not just mine.
The process is exactly the same for addons and themes, except themes have an extra step of activating the theme after installing.
Sometimes step 3 above can run out of PHP execution time. This is most likely when installing an addon or theme that installs a large amount of sample content. You should not run into such an issue with any of my addons or themes.
If you do run into such issues, you can run the install manually from the shell command line.
$ concrete/bin/concrete5 c5:package-install my_package_handle
or
$ concrete/bin/concrete5 c5:package-update my_package_handle
When updating, be sure to replace the previously installed package directory rather than adding to it. If not, you could end up accumulating obsolete debris from a previous version of the package. In general you should not uninstall - uninstalling will loose existing data and blocks. Just replace the /packages/_addon_handle_/ directory with the unzipped package update.
If you find yourself often needing to install or update many addons or themes manually, consider my Package Magic addon. Once Package Magic is installed, through the marketplace or manually, all further installs can be handled from the site dashboard using Package Magic. If you build custom code in packages, Package Magic can do a lot more. Package Magic can analyze package structure, zip up packages, upload and download zip files directly to various stores.