Once anapp catalog site is created, you may proceed to add the SigningHub for SharePoint package on it. It will provide an alternative way to your end users to install the SigningHub for SharePoint add-in from their organisation, instead of accessing the SharePoint store for it.
This is also helpful in maintaining a centralised location to add and upgrade the packages, so that all the end users of an organisation can access the same latest versions.
Add the SigningHub package in your app catalog site
Log into your Office 365 account with SharePoint administrator credentials.
Click the app launcher icon in the upper left and select the "Admin" option, as marked with red arrows on the below screen.
The Office 365 admin menu will appear in the left panel. Click the "Admin Centers" option and select the "SharePoint" option.
Click the "apps" option from left panel.
From the next appearing screen, click the "App Catalog" option.
Click the “Apps for SharePoint” option.
Click the “New” option.
Browse the SigningHub for SharePoint package from your system and click OK.
The package file can be downloaded from the SigningHub website.
The package will be uploaded, and is added in your catalog site. It is now available to your end users for installation from your organisation.
Upgrade the SigningHub package in your app catalog site
When a new version of SigningHub for SharePoint add-in is released, you can upgrade its package on your catalog site to make it available for your end users.
Log into your Office 365 account with SharePoint administrator credentials.
Click the app launcher icon in the upper left and select the "Admin" option, as marked with red arrows on the below screen.
The Office 365 admin menu will appear in the left panel. Click the "Admin Centers" option and select the "SharePoint" option.
Click the "apps" option from left panel.
From the next appearing screen, click the "App Catalog" option.
Click the “Apps for SharePoint” option.
Click the “New” option.
Browse the SigningHub for SharePoint package from your system and click OK.
The package file can be downloaded from the SigningHub website.
If the version of selected package file is newer than the available package, then it will be upgraded.
The newly added package is now available to your end users for installation from your organisation.
How the end users will be notified for this upgrade?
When you upgrade the existing package of SigningHub for SharePoint on your catalog site, the end users of your organisation will see the "Update" link along with their installed version on the site collection, as shown below.
They may click it to install the latest package.