Time Machine permission error with remote disk destination (w/ solution)

I was having problems using a remote disk as a Time Machine destination. It was complaining that the account did not have permission to read, write, or append to the volume.

I had made sure that I had enabled sharing for the drive in System Preferences, and I had ensured that I enabled the drive as a Time Machine destination withing sharing advanced options. I had ensured that the account being used was an administration account.

It turned out that the problem was that the disk needed custom permissions; I used "get info" to add read and write permissions for the administration account being used.