You want to create a backup plan to a local/network storage with replication to cloud, but the initial upload of full backup to cloud would be time-consuming as the amount of data to back up is large.
You can use InitialSeedingTool to upload first backup from another computer with sufficient bandwidth.
1. Create a backup to your first local/network destination. Make sure the Backup format is Version 12. In Schedule, keep the Always incremental backup scheme.
2. Once the backup is completed, copy it and the cloud certificate (see How to find certificate) to the machine from which you will upload it to cloud.
3. On this machine, install Acronis InitialSeedingTool as described in this article.
4. Upload the backup to cloud as described here.
5. In the backup plan, add replication to cloud.
Next time the backup plan runs, it will save changes only; this incremental backup won't take as much time as a full backup would.