Hi SamSONACA
the capacity is not a problem for both services.
Both services, Azure Fileshare (AFS) and NetApp Files (ANF), are suitable for your goals.
Azure offers with Azure File Sync a easy migration service, to move your On-Prem Fileshares to an Azure Fileshare - this also possible with NetApp Cloud Sync.
From my point of view Azure File Sync is a bit easier and more cost efficient.
The key difference between AFS and ANF is how they work.
Azure Files is a PaaS solution with a public endpoint and the AD integration is a bit tricky compared to NetApp Files.
NetApp Files only working inside a specified Azure VNET and has a better or easier AD integration.
For your data capacity, I think you can work with Azure Fileshare. Additionally use Private Link so that the Azure Fileshare gets a private IP and SMB authentication. For the migration use Azure File Sync to migrate the files from a local fileserver to Azure.
Perhaps the following article can help you gain some insight into how Azurefileshare can work as a file server replacement:
https://www.reimling.eu/2020/12/azure-files-enabled-ad-ds-smb-authentication-all-you-need-to-know/
Greetings
Gregor