Applications in Azure how connect to Microsoft Exchange on-premise

Dear All,

We are moving an application to Azure from on-premise which uses on-premise exchange 2019. The application will be moved as it is life and shift. Once the application is moved to Azure can you guide how the application will be authonicating back for exchange activity, We will have a local domain controller in Azure on VM

Any changes needed in Exchange on-premise server side?

Any change needed on the firewall side on both the ends (like SMTP)

Any changes needed in the application?

Please guide

Regards, AzureBeginner