Total novice, who likes helping beginners get started?

It's great that you're looking to set up a disaster recovery solution using AWS Glacier for your video archives. Many beginners find AWS services challenging at first, so you're not alone in feeling overwhelmed. Let's break this down into simpler steps to help you get started.

First, it's important to understand that Amazon S3 Glacier is primarily designed for long-term, low-cost storage of data that is rarely accessed. For your use case of backing up from a Synology NAS, it's actually recommended to use S3 with Glacier storage classes rather than using Glacier directly.

Here's a simplified approach you can try:

1. Start by creating an S3 bucket in the AWS console. This will be easier to work with than Glacier directly.

2. When creating your bucket, you can choose the S3 Glacier Flexible Retrieval (formerly S3 Glacier) or S3 Glacier Deep Archive storage class. This will give you the cost benefits of Glacier with the easier management of S3.

3. For user access, create an IAM user with programmatic access. This will give you an access key ID and secret access key.

4. Attach a policy to this user that gives it permission to access your S3 bucket. You might start with the AmazonS3FullAccess policy, but for better security, you should create a custom policy that only allows access to your specific bucket.

5. Use these credentials in your Synology Hyper Backup application. Make sure you're using the S3 backup option, not the Glacier option.

If you're still getting "insufficient permissions" errors, double-check your IAM user's permissions. Make sure they have rights to list buckets, and read/write objects in your specific bucket.

Remember, it's okay to start small. Try uploading a small amount of data first to test your setup before attempting to backup all 7TB.

If you continue to have trouble, don't hesitate to reach out to AWS support or consult their documentation. They have extensive guides and tutorials that can help you through the process step-by-step.

Lastly, keep in mind that while AWS services are powerful, they can have a steep learning curve. Take your time, be patient with yourself, and don't be afraid to ask for help. Many AWS professionals started exactly where you are now!
Sources
Community | 5 Tips I Wish I'd Known When I Was New to AWS
What Is Amazon S3 Glacier? - Amazon S3 Glacier