I'm unable to install the plugin. Get the following fatal

Hi,

I'm unable to install the plugin. Get the following fatal error:

Parse error: syntax error, unexpected T_PAAMAYIM_NEKUDOTAYIM in /kunden/402042_59597/gruenderkey/wordpress/wp-content/plugins/membership/app/model/class-ms-model-customposttype.php on line 426

Could you help me out?

Thanks,

Best Julian