Thank you.
The issue here is that I have several backup folders under C:\ProgramData\NCH Software\ExpressInvoice and I have several backup folders inside each backup folder!
That is why the folder size exceeded 6GB and the backup process took fovever.
I'm now manually deleting all folders including "backup" in their names and also folders like ExpressInvoice1588248953 which are located under C:\ProgramData\NCH Software\ExpressInvoice.
I think all other folders should be fine but I'd like to double check, if possibile, the standard content of C:\ProgramData\NCH Software\ExpressInvoice.
Thanks!