Laravel 5.3 Slack integration

I need to get access to Slack’s Event API from my Laravel 5.3 application. I have installed vluzrmos’s package from GitHub, but I can’t get it to work properly. I ran through all the steps in the installation, but when I try to do SlackUser::lists() in my Controller I get an error like this: Non-static method VluzrmosSlackApiContractsSlackUser::lists() cannot be called statically, assuming $this from incompatible context.

Could you help? Thanks

Source: stackoverflow-php