Thank you for reaching out to us, As I understand you are trying to update reply URL as "msauth://com....." for your application registered in Azure AD, As per this documentation - https://learn.microsoft.com/en-us/azure/active-directory/develop/reply-url supported schemes for reply URL should start with https or http ( examples are provided in the document how reply URL should be defined).
However if you want the reply url to be "msauth://com...." you can navigate to Manifest option and edit the url as per your requirement and edit the url type as "installed client (check below image 2)"
the same process as mentioned to update the manifest file.
Let me know if you have any further questions, feel free to post back.
Please remember to "Accept Answer" if answer helped, so that others in the community facing similar issues can easily find the solution.
Thanks
Deepanshu