Status: New Tech Update - Wed Aug 26 - 8:53 AM
So I have ensured that the cache has been created here:

[root@hw001 vz]# vzpkg create appcache --ostemplate centos-7-x86_64 --apptemplate devel
Can not find 'centos-7-x86_64' EZ os template
Some template(s) centos-7-x86_64-ez is not found, running /usr/bin/yum to install it...
Loaded plugins: fastestmirror, priorities
Loading mirror speeds from cached hostfile
* virtuozzo-os: mirror.supremebytes.com
* virtuozzo-updates: mirror.supremebytes.com
126 packages excluded due to repository priority protections
Package centos-7-x86_64-ez-7.0.0-5.vz7.noarch already installed and latest version
Nothing to do
Can not find 'centos-7-x86_64' EZ os template

As you can see it says it is already installed "Package centos-7-x86_64-ez-7.0.0-5.vz7.noarch already installed and latest version"

Then trying to create the container with the basic config:

[root@hw001 vz]# vzctl create 101 --ostemplate centos-7-x86_64 --config basic
Unable to get appcache tarball name for ve-basic.conf-sample with ostemplate centos-7-x86_64
Destroying Container private area: /vz/private/101
Warning: Container is in old data format, unregistration skipped
Container private area was destroyed
Creation of Container private area failed
[root@hw001 vz]#

Also here is the basic config:

[root@hw001 conf]# ls
networks_classes ve-confixx.conf-sample ve-vswap.2048MB.conf-sample ve-vswap.512MB.conf-sample vps.vzpkgtools.conf-sample
ve-basic.conf-sample ve-vswap.1024MB.conf-sample ve-vswap.256MB.conf-sample ve-vswap.plesk.conf-sample

"ve-basic.conf-sample"

Here are its contents:

# This is an example configuration file for so-called "basic" Container.
#<agent>: Configuration file for allocating 256 Mb of memory.
#
# Copyright (c) 1999-2015 Parallels IP Holdings GmbH. All rights reserved.

VERSION="2"

ONBOOT="yes"

PHYSPAGES="65536:65536"
SWAPPAGES="65536"
# Virtual memory overcommitment
# privvmpages = (ram + swap) * VM_OVERCOMMIT (unlimited if not specified)
#VM_OVERCOMMIT="1.5"

CPUUNITS="1000"

NETFILTER="stateless"

DISKSPACE="10485760:10485760"
DISKINODES="655360:655360"

QUOTATIME="0"
IP_ADDRESS="0.0.0.0"

ARCH="x86"
PLATFORM="linux"