We deploy NEOS office plug-ins using Microsoft 365 Integrated Apps to groups of users. Assembly software provides both as Add-in (Custom apps) for Microsoft 365. They are not available via the marketplace (although there is a NEOS listing for the solution itself).

The Neos Add-in for Outlook allows you to file emails into a case from Outlook Web, desktop or mobile. You can also use the add-in to view Party and Provider contact information. 

The Neos Outlook Add-in is supported and installed on individual Microsoft 365 accounts. For users that have multiple Microsoft mailboxes, the add-in must be installed for each additional account in Outlook Desktop. 

Outlook Web will only show one mailbox account in a browser session. To use the add-in for another Microsoft 365 email account, open an incognito

browser session and log in using the second email. Install the Neos Outlook Add-in for that second account, then switch between browser windows to tag emails from the different mailboxes.

https://saasuicdn.blob.core.windows.net/neosoutlookplugin/manifest.xml

This add-in is also called "Neos Office Plugin". This new version of the Microsoft Word online add-in has all the features and functionality of the Word desktop add-in with additional enhancements to the user interface. The Neos Word online add-in can be used to create and edit existing templates using Word online or Word for Mac. 

This is from their documentation.

If your firm plans to utilize Two-Factor Authentication, each user must update to the latest Word online version PRIOR to enabling 2FA. 

To ensure that Neos data generates properly, Tags should not be modified unless noted in the Advanced Document Coding for Word article. 

https://saasuicdn.blob.core.windows.net/neosofficeplugin/manifest.xml