No, essentially that is the number of recording channels that can be in us at one time... if you have 4 extensions in your recorder hunt group, 4 users can actively be using Record-A-Call simultaneously, if a 5th one attempts it they will get an error message.
The capacity of the embedded system is limited to about 150 hours of storage, and this includes record calls, voicemail messages, and greetings combined, so if you have people recording a lot, this can get full quickly... 4 people recording an hour every day, 5 days a week, and your VM will be full in 2 months so remember to delete these regularly or setup voice mail to email and force delete them. Also note that each individual mailbox has a maximum capacity of 100 messages/recordings.