Do you have root access via ssh ? If yes then using a wget command as root is a nice approach - use that often myself.
nope i dont. i cant ssh to the host
There are ways to use a VM to write directly to a datastore - but the only convenient option requires root access to the esxi via ssh.
Consider sending an email to your provider:
Hello - I welcome that you make sure to restrict unwanted access to the VMs we pay for,
As I assume that then you consequently need a supported way to allow your customer to upload files to those VMs.
I could not find a link where I can upload an iso and request your support team to upload it - please forward this mail to the correct address.