The storage limit check is performed before the backup is run. That's why it is short-circuiting the backup. If you are using a version of the product with a 5TB storage limitation, you have a few choices:
1. Reach out to sales and see if they can raise your storage limit to 10TB. If I recall, that can be done for a fee
2. Separate the Local and Cloud backups so if you hit the 5TB limit, you can continue to run local backups
3. Check your retention settings and make sure you are not keeping data for longer than needed and are not keeping more versions of files than needed.
4. If you are running Block-Level backups, make sure your full backup schedule works with your retention settings. For example, if you keep 7 versions and have a 7 Day full backup cycle, you may end up keeping 14 versions until the oldest 7 day set can be deleted.
5. Make sure you are not backing up any folders you do not need to protect. Like internet cache and temp folders.
6. Look on your hard drive for the largest files you are backing up and consider manually deleting some of the backup versions from the cloud using the Storage tab in the product. That may free up the needed space so you can run a backup, and combined with other changes above may help avoid hitting the storage limit again in the future.

So basically knock out some of the Cloud Backups. I don't know if they would increase it for a fee, and when I try to buy the better software they say its for MSPs. Why is there a limit anyways?!

I'm backing up 500 gb of data each week!

It's 500gb of data each week. That gives me only 10 weeks worth of backups.

It's a long and complicated question. You can buy a 10 TB upgrade. I forget the price, but if you ask the team they will let you know what it is.

Are you saying that you are only backing up 500 GB worth of data in total? If so, what are your retention settings for Versions and Duration of storage and your backup schedule for the Incremental and Block-Level (backup terms may be different based on your version)?

Yes, I'm only backing up 500GB in total (so that 5TB limit in the cloud is from previous copies of the backups). Perhaps I'm retaining them too long? I have Google Cloud set to 1 year; is that normally too long?

I'm hesitant to purchase additional upgrades because, in the event of a disaster, I'll lose the OS and be unable to deactivate the software in order to move it to the new install. I've had to purchase a new copy for certain apps in the past because of that limitation (which is not funny).

I'll reach out to support to ask about the size increase.

or you can provide me the information I requested above and maybe we can figure out why you're using that much storage. You should not be using that amount if you're only backing up 500 GB and you're using the right options.