Dear Enzo,
To set access rights for application, please do the following:
1) Select shared COM6 port in the tree;
2) Press Edit button in the toolbar;
3) In "Set custom rights for this application" textfield specify the full path to the application you want to set custom access rights for;
4) Please, toggle "Read", "Write" and "Control" options;
5) Click "Set custom rights" button to modify access rights;
6) Press Update Settings button;
7) Open the COM6 port in your application;

Check, whether the application sends and receives the data correctly.
Thank you.