RN628x with 8 6tb Hdd and need to backup aprox 60 peer to peer pcs RN628X

I'm not completely sure what you mean by the peer-to-peer PCs. From the full post, I am guessing that there is an enterprise VPN connecting three sites, so that the PCs on those sites would always be able to reach the NAS.  Also, I am guessing that the three off-site PCs can connect to the enterprise network using a VPN client.  The NAS itself is at site 1.  Let me know if those assumptions are correct.

Knowing if the customer needs to comply with HIPAA might also be relevant (and which devicees store ePHI).  For instance, the relatively few iPads could be backed up to Apple's iCloud - but that is not HIPAA compliant. There is brief analysis for iCloud here:  https://www.hipaajournal.com/icloud-hipaa-compliant/

Trying to use backup jobs on the NAS would be difficult - partly because you have so many devices, and partly because you have little/no control over when the PCs are actually turned on.  I'm not a fan of using ReadyCloud backup - it's quite restrictive on what folders can be backed up.  

Personally I'd look at something like FreeFileSync on the PCs - setting it up with a ReadyNAS share as the destination.  That particular package is free (even for commercial use).  Backups could be scheduled (or not) as you wish.  It'd be simplest if the three folks who aren't at one of the three main locations run the backups manually when they are connected to the enterprise network. But that would require some discipline on their side (to actually run them).

You could potentially use the Home share feature of the ReadyNAS (making a home share the backup destination for each PC).  That would require a user account to be set up for each user, and you'd also want to make sure that the NAS username and password either match the PC login, or are entered as a Windows Credential on the PC..

You don't say how those iPads are used, or what data is actually on them - so it's not obvious whether they actually need to be backed up.

If they do, there are some iOS apps out there that can back up an iPad (or an iPhone) to a network share.  So perhaps look into those for the five iPads. Those tools would only work if the iPad is connected to the enterprise network (either directly, or with a VPN connection).

Resilio sync could also be used (and would work even when the iPads aren't connected to the enterprise network) - though I've never tried to do that with the NAS, and you might run into issues with multiple iPads.  If the iPad users also have a PC, then one strategy is to use Resilio Sync to back up the iPads to their PCs, and then use FreeFileSync to transfer that data to the ReadyNAS.  Resilio Sync wouldn't be free for commercial use, so you would have to price that out.