If the other nodes are clustered properly (and have Disk-Groups created then they should see vsandatastore to be of size (can easily be validated via SSH with df -h).
Regarding the non-clustered node: check that this has a vSAN-enabled vmk on the same subnet as the other nodes have this, with correct MTU and that it can reach the other nodes (e.g. with 1500 MTU: # vmkping -I <vSAN vmk> -s 1472 -d <destination vSAN vmk IP>
Are all your hosts in maintenance mode ? Datastore will be 0tb if they are.