Android enterprise device owner management mode

Hi Team, 

First of all, I would like to thank you all in advance for helping. My issue is as follows. 

As per one of my customers requirement I did a Sophos central MDM POC. Devices which were used was "Huawei Y2 Pro" with Android 8.0. Customer wanted to do the following

01. Block App install

02. Block App uninstall

03. Block android "play store" So that clients cant install any app.

04. Use Sophos URL filtering through Sophos mobile security App

05. Use Sophos secure work space for distribute documents through out the devices. 

I created a android profile and policy and added them in to a task and deployed it to the devices. everything was working fine except for profile gets disable time to time and clients can do anything on the devices. They can even remove the SMC app as well. So after getting support from the Sophos support they told me that this is happening because that this is a Huawei device and instructed me to install the devices in Android enterprise device owner management mode. Now the devices are on the enterprise device owner management mode App uninstall blocking and app installing blocking is working. In order to block play store I created a app group and added "com.android.vending" to that list. with that I was able to block play store as well. Now following are the issues which I'm facing currently. 

01. After blocking "com.android.vending" I can brows anything on the devices but when I try to open a link it gives me a message saying No app was found to open the link. 

02. I'm unable to create a task to deploy the apps. When I try to do this I gets an error. (How can we create android enterprise tasks?) (please see image 1)

I highly appreciate If someone can tell me how to do this step by step.