To use Pear Deck with a Google Apps for Education domain, Pear Deck requires that the domain allow third-party apps to be installed on Google Drive (which is enabled by default in the Google Admin Console) OR that the administrator install Pear Deck from the Google Apps Marketplace.
If your domain currently disallows third-party apps, your Google Apps IT Administrator will need to perform the following steps to re-enable apps:
An alternate method...
Google Apps Marketplace applications can be installed by administrators. You can therefore whitelist Pear Deck for your organization by disabling the option above for your users, then deploying specific Marketplace apps (like Pear Deck) as the administrator.
Original Source: https://support.google.com/a/answer/6105699?hl=en