About this Add-on
All the add-on does is to set one preference ldap_2.servers.outlook.dirType to enable the Outlook address book in TB. You can even do that manually without the add-on. Please refer to the respective release notes at https://www.thunderbird.net/en-US/thunderbird/91.0/releasenotes/ and note:
Access to Outlook Contacts; To enable, set ldap_2.servers.outlook.dirType to 3; This setting may cause startup delays. Typically the delay is a few seconds.
When the add-on is used, the local Outlook address book is shown in Thunderbird's address book tab, by default labelled "Contacts". If it doesn't show, Outlook wasn't properly installed. It works fine in TB 115, just tested on 21st Oct. 2023 with latest Outlook/Office 365 install (but also working with older versions).
The so-called Global Address List (GAL) from the Exchange server is NOT supported by Thunderbird. To access it, you need the Owl add-on, or TbSync once its respective component is fixed.
Off-topic: Users who don't want to access the Outlook address book from Thunderbird can migrate their Outlook contacts permanently to Thunderbird. That can be done by Thunderbird's in-built import which only covers simple cases, or via the guide that can be found here. Using the CardBook add-on, categories are also supported in Thunderbird. Outlook and CardBook also support "Gender" and numerous phone types which the default Thunderbird address book does not support.