The plugin wasn’t updated in two years, and it seems to be abandoned, but they are still taking money from their premium plugins.
The code is really poor and too big to be reviewed properly, and the scan seems to suggests that there is PHP object injection, unsafe cookie creation and some sanitisation functions that are not inherently safe.
Suggestion: find an alternative
Reason for the 'Potentially unsafe' result
The plugin has been given this recommendation at the tester's discretion: