How to automatically apply permissions to files added to a shared folder
I believe the way to resolve this is to set up ACL inheritance permissions on the parent folder. More about this here.

Firstly enable ACL permissions for SMB shares with the following command. 

sudo defaults write /Library/Preferences/SystemConfiguration/com.apple.smb.server AclsEnabled -bool YES


Then set up inheritance permissions on the parent holder with the following command. This should recursively go through your share and apply the relevant permissions.

sudo chmod -R +a "group:REPLACE_WITH_YOURGROUP_NAME:allow readattr,writeattr,readextattr,writeextattr,readsecurity,list,search,add_file,add_subdirectory,delete_child,file_inherit,directory_inherit" REPLACE_WITH_PATH_TO_PARENT_SHARED_FOLDER


To be safe I'd recommend creating a test share to try the chmod command before applying it to your company's share. Then once you are sure you get the right results apply it to the live/production share.