I am a guest account.
How can i download vMX?
you can go to https://support.juniper.net/support/downloads/ and choose "vMX Eval". You can try to download it there.
If this is not possible, you could open an Admin Service Request to ask for a (one time) download permission.
You can find more details how to open a Service Request here:
I don't have access to case manager.
At the mentioned website, there are lots of telephone numbers documented. You can call them directly, no need for a mandatory case manager.