If you're having trouble finding the download or don't have a Juniper account, you can also try:
: Current Juniper customers or newly registered users can access a trial version. Visit the vMX Trial Download Page to request access and a license key. vJunos-router (Alternative)
with a valid service contract or Software Support Reference Number (SSRN). Version Selection
It looks like you’re trying to locate and download the with the filename vmxbundle-17.1R1.8.tgz (or similar based on your string 171r18tgz , likely meaning 17.1R1.8 ) and want it to work in a 2021 environment.
Access the Juniper Support Downloads page and select the vMX product.