Based on your older post, I will assume that your accounting software is running on a windows vm on your macbook pro.
Parallels RAS is meant mostly for business setups with "fixed" servers (fixed hostnames) and a domain-based infrastructure. As such, Parallels RAS might not be a good fit for you.
There are a few solutions based on your use case/setup:
Case 1: Your assistant is using the accounting software directly on the vm
Option 1: Using parallels access they will be able to access the windows machine and account software on it as long as your macbook is connected to the internet. However since parallels access gives "local-like" access only one of you will be able to access the windows machine at the same time.
Option 2: If your assistant is using something else (such as RDP) then one option is to connect to the work vpn or configure a vpn server at your back office (and open that vpn server to the internet). If both you and your assistant connect to the same vpn it will be like being on the same network.
Option 3: If there is no back office to speak of, then you might need to configure a dynamic dns on your windows machine. This will give you a fixed hostname anywhere you are so your assistant (and anybody knowing that hostname) can connect to the software on your windows machine. You can increase the security of your setup by also setting up a vpn on the windows machine and blocking all access from the internet except for the vpn.
Case 2: Your assistant is using "client" accounting software on his own machine to access the "server"
In this case, you can try options 2 or 3 above unless you can switch to case 1.
