This is the Snapp Automotive repo manifest to check out the AOSP based Snapp Automotive image.
To checkout the complete tree you should follow the AOSP instructions, but, where they say
repo init -u https://android.googlesource.com/platform/manifest -b master you should, instead, run;
$ repo init -u https://github.com/snappautomotive/firmware-repo-manifest.git -b sa-main
When you select a lunch target you should choose snapp_car_x86-userdebug (or -eng if you want to do low level debugging).