How to create the admin account

php bin/grav newuser

bin/grav new-user has been deprecated in favor of the new bin/plugin login new-user

do i just create admin.yaml manually?

No, just use this new command bin/plugin login new-user instead of the old one. Did you read the old one somewhere? So we can add the new command instead

Sorry my bad. the error message actually told me what to do. i though it was just an explanation. thanks for your help.