Does app registration on the Azure Portal require any changes to intranet deployment using ClickOnce?

Question

Microsoft has announced its intention to turn off SMTP AUTH:

https://docs.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/deprecation-of-basic-authentication-exchange-online

This change will affect an application I wrote for internal use by employees of the company. The app pulls info from the company database and merges the data into an email which is sent to designated business partners. The app connects to the Outlook SMTP server and, at present, is authenticating with account-name and password.

The app is launched from an intranet web server using ClickOnce and is set to be "available only online".

According to the documentation for setting up OAuth authentication, the application must be registered on the Azure Portal in order to obtain an OAuth token which would be used by the app when authenticating on the SMTP server.

Will this portal registration have any impact on how the application is made available to the users? Can we continue to launch the app from an intranet web server using ClickOnce?

EDIT: The following documentation appears to address some aspects of my question but I don't know, for sure, what is meant by "if you're not registering the application in a directory" and "outside of a directory" in the context of ClickOnce deployment where the application package is placed in a folder on the web server:

https://docs.microsoft.com/en-us/graph/auth-register-app-v2

Accounts in this organizational directory only

Select this option if you're building a line-of-business (LOB) application. This option is not available if you're not registering the application in a directory.

This option maps to Azure AD only single-tenant.

This is the default option unless you're registering the app outside of a directory. In cases where the app is registered outside of a directory, the default is Azure AD multi-tenant and personal Microsoft accounts.