Limiting access within shares

I use My Cloud Pro Series 4-Bay NAS, for work purposes. I have created various shares for my staff members. There are certain shares where I want every staff member to have access to the main folder and then limit access to the sub-folders, e.g. I created a share names ‘client folders’, within that share there is a number of clients, I would like to limit the access to those clients, e.g. staff 1 has access to client A but no access to client B and staff 2 has access to client B but not to client A. I cannot create separate shares per client as that will mean creating over 100 shares, it will just be a mess. PLEASE HELP!

Unfortunately. there is no option to provide access on different folder to user. It is required to create shares of different data accessible by particular user.