You can install the Outlook add-in manually with a process called side-loading if it is enabled for your organisation. If your organisation has added RICOH Spaces as an organisation app there is no requirement to follow the following steps. A full guide on the side-loading process can be found on Microsoft's support site.
Installing on desktop
The Outlook add-in is used during the event booking process within the Outlook client. This means you must go to your calendar page and then use the new event option.
Depending on your Outlook client you will see an option at the top of the screen, for most Windows users it will be the "Get Add-ins" button.
Mac users may need to use the "3 dots" menu labelled to see more items. Then click the "Get Add-ins" button.
Head over to the My add-ins' section
Select Add a custom add-in
You can now add from URL or File.
Add by file (recommended)
To download the file, please download the file in the attachment area below to your machine and select it when requested. Download.
Add by URL
You can easily add it by adding the following URL into the box when requested in the above process. https://firebasestorage.googleapis.com/v0/b/rs-apks/o/Outlook%20Addin%2Fmanifest-prod.xml?alt=media&token=4e8ee010-37a7-4d5b-811b-5ce74bd86002