HostPoolName xxxx does not exist ?!

So seems like I was running AzureWVD on 2020 Spring realease and I was following old guides related to previous version.
Thank You Soo Kuan Teo It´s solved now as you point me to the key.
Steps to solve the issue:

1-) PowerShell 7
https://github.com/PowerShell/PowerShell/releases/download/v7.1.0-preview.3/PowerShell-7.1.0-preview.3-win-x64.msi
2-) Azure Powershell Module
https://docs.microsoft.com/es-es/powershell/azure/install-az-ps?view=azps-4.2.0
3-) Azure UI Wizard HostPool Creation was run previously with success including vm creation, entitlements and permissions, but GET-AzWvdRegistrationInfo outputs no data, just an empty token value. So to get the token I run:
New-AzWvdRegistrationInfo -ResourceGroupName <resourcegroupname> -HostPoolName <hostpoolname> -ExpirationTime $((get-date).ToUniversalTime().AddHours(2).ToString('yyyy-MM-ddTHH:mm:ss.fffffffZ'))

Note1: Once step 3 was done. My published WVD Desktop and apps resources were finally showed up! (Eureka!) But fails connecting to them. So keep pushing!
Note2: I Skipped the role assignment step since it was done previously on Azure UI

5-) Token to a VAR & VAR content to a TXT
$token = Get-AzWvdRegistrationInfo -ResourceGroupName <resourcegroupname> -HostPoolName <hostpoolname>
$token | select-object token | format-list > C:\TOKEN.TXT

6-) RDP to the WVD vm. Download and install WVD Agent: https://query.prod.cms.rt.microsoft.com/cms/api/am/binary/RWrmXv
Paste the step 5 token into the Agent Installer Wizard
Download and install WVD Agent Bootloader:
https://query.prod.cms.rt.microsoft.com/cms/api/am/binary/RWrxrH

Note3: I think the whole steps would have to be completed automatically by the HostPool Azure UI Wizard, but for some reason it didn´t happens, maybe an error or maybe it´s as is by design.
In fact running appwiz.cpl after Install WVD Agent with the token on my wvd vm shows 4 entries for "Remote Desktop Services Infrastructure Agent" with build numbers:
1.0.1.7
1.0.1932.4800

1.0.1932.6700
1.0.216.900
(Very Weird)

Note4: The Bootloader Agent didn´t install as the same build version 1.0.0.0 seems to was already installed on that machine.
Anyway, SUCCESS!