Can Allmoxy allow us to set the default permissions when a new customer signs up?

We want to restrict everyone from placing orders when they first sign up.

No, the default permissions are set automatically, the best way to handle that is usually to use a trigger for someone in your company to do whatever needs to be done for a new sign up - so in this case maybe someone needs to call or email the new sign up to verify who they are and give them info on ordering. Even if they place an order as soon as they sign up, you can avoid verifying the order until someone has made contact with them.

In the meantime, I do think this might be a request that other companies would also like so I'll put it on our list to discuss.