Thread for Email Installation Failed

Thread for Email Installation Failed

Getting this error when installing Thread for email using the link ( https://appsource.microsoft.com/en-eu/product/office/WA200004673?tab=Overview )

Open Outlook on the web ( https://outlook.office.com/ ) and go to  "Get Add-Ins" tab as highlighted

 Search for Thread for Email then select it

Click Add to install it