Error 'Something went wrong and we couldn't start this app' in Outlook Integration

To resolve this error, the Office 365 or Exchange Online administrator must enable the Salesforce Outlook Integration add-in through the Exchange Admin Center (EAC). The Exchange Admin Center (EAC) is the web-based management console used by administrators to manage Microsoft Exchange settings for the organization.

Steps to Enable the Salesforce Outlook Integration Add-in

1. Sign in to the Microsoft 365 Admin Center at admin.microsoft.com using administrator credentials.
2. Navigate to Admin centers > Exchange to open the Exchange Admin Center.
3. In the EAC, go to Organization > Add-ins (or select Apps in the newer Exchange Admin Center).
4. Click the + (Add) icon and select Add from the Office Store.
5. In the Office Store search, type "Salesforce" and locate the Salesforce Outlook Integration add-in.
6. Click Add to install the add-in for the organization.
7. Once installed, click on the add-in in the list and set the deployment status to Enabled.
8. Configure the add-in to be available for the relevant users or user groups.
9. Ask the affected user to close and reopen Microsoft Outlook or Outlook on the Web to trigger the add-in reload.
10. The user should then attempt to open the Salesforce Outlook Integration add-in panel again.

If the error persists after following these steps, confirm that the user's account has the required Exchange Online license and that no conditional access policies are blocking the add-in.

For more information, please visit below Microsoft resources:
Install or remove add-ins for Outlook for your organization
Manage user access to add-ins for Outlook in Exchange Online