Laravel Guzzle Login or Frontend Login page?

Hi there, in my project Im using Graph Api with Guzzle and all works realy nice. So now I want to use Guzzle for my KeyCloak Api, too. But if I try to do a login it failed and send out a Curl Error: cURL error 60: SSL certificate problem: unable to get local issuer certificate I tried to connect in my frontend before and read a lot about login, but didnt find any solution. Is KeyCloak only usable with Login page by KeyCloak? I tried over frontend and backend. And I was wondering, because in Postman all works fine.
Thank you very much!