HI Zaur 

Do you have Google Play services set up in your project?

If not you can do this by using unreal's  Online Subsystem.

You can also find a post about Goggle play set up for Unreal here 

Using the Online Subsystem you should be able to get the access token which is needed by the Goggle Play Connect  request.

Regards

Katie

Refer to this for more details on each input flow: https://docs.gamesparks.com/api-documentation/request-api/authentication/googleplayconnectrequest.html

Cheers,

Omar