Zenup install error

Hi There, i'm trying to install Zenoss 4.2.5 as per documentation.

I got most of the way through until i got to "2.10.4 Start Zenoss Core and Install the RPS"

when i run zenup install:

zenup install zenoss_core-4.2.5-SP457-zenup11.zup

i get the follow error:
Calculating local diff
Error while running command install
Traceback (most recent call last):
File "/opt/zenup/python/zenup/zenupcli.py", line 51, in __init__
run()
File "/opt/zenup/python/zenup/zenupcli.py", line 449, in _install
force=self.args.force)
File "/opt/zenup/python/zenup/zenupapi.py", line 308, in install
result = product.install(zup, force)
File "/opt/zenup/python/zenup/zupproduct.py", line 584, in install
no_hotfix=no_hotfix)
File "/opt/zenup/python/zenup/zupproduct.py", line 400, in _test
for patch in pgen: pass
File "/opt/zenup/python/zenup/archive/zup.py", line 137, in apply_patches
os.chdir(cwd)
OSError: [Errno 13] Permission denied: '/root/Downloads

I'm not sure why this is. I have however understood " Log in as zenoss" to mean "su zenoss". If i try and logout of root and login as Zenoss user, i get prompted for a password i didn't set!

Any Ideas

Thanks