Managed backup large database to Azure
Reference:


Backing up a VLDB to Azure Blob Storage by Dimitri Furman
Understanding Block Blobs, Append Blobs, and Page Blobs
SQL Server Backup to URL


With your size you should be able to use page blog and specify MAXTRANSFERSIZE = 4194304 and BLOCKSIZE = 65536.
If you need to backup databases greater than 1TB use block blob and striped backup. To use block blobs, you need to create a Shared Access Signature (SAS), and create a credential for the SAS.  There are examples in the third reference above. 

There are bunch of questions answered in the comment section of the first reference that will help in case if you run into any issues.