If you want to only access the hard drive, I assume you can... if you want the time capsule to extend the range, you'll be negating the benefit of a true mesh router system.
I'd suggest you get a network attached drive and just plug that into one of the velop units. Timeports are no longer supported by apple...so you'll be SOL anyway if there are issues. I replaced a time port setup with these and they work much better than time port.