fatal T_PAAMAYIM_NEKUDOTAYIM error keeps showing up

I keep getting this error and was not fully helped the last time I asked for assistance. Here is my error message:
Plugin could not be activated because it triggered a fatal error
Parse error: syntax error, unexpected T_PAAMAYIM_NEKUDOTAYIM in /home3/scottolm/public_html/wp-content/plugins/pro-sites/pro-sites-files/lib/ProSites/Module/Taxamo/lib/Taxamo/Swagger.php on line 185

I have installed the plugin via ftp, through the dashboard, and uploaded it into plugins and have the same error message every time.