How to set wildcard DNS record for Azure Virtual Machine w Linux?

I'm trying to deploy WorkAdventure for test in an Azure Linux Virtual Machine with Linux, and access it from the internet.

For this I found here #794 (comment) a reference to a good documentation from insensitiveclod from technic.
I followed that guide, and did most of the steps in an Azure VM with Ubuntu 20.04.2 LTS, dynamic IP address and with a DNS name like mytestwa.northeurope.cloudapp.azure.com

I did:

• Create Azure VM with Linux
• Create Azure IP Address (public address and DNS name) and assigned to Azure VM
• Set up docker environment and network setup
• Set up Traefik (and coturn) seperately from jitsi/workadventure
• Set up WorkAdventure
• Set up Jitsi

Still, I can't test anything (Traefik, WorkAdventure, or JITSI) because I don't know how could I achieve this step from the guide: "Set a wildcard DNS-record for *.whatever.your.domain.is to the publicly reachable IP of the machine you want to host it on. Using a CNAME record works fine. It might be good to set TTL to 5mins at first. (create DNS wildcard or each DNS entry for every services xyz.whatever.your.domain.is)"

Hence, WorkAdventure will need to use subdomains (play.*, pusher.*, meet.*, etc.) and I can't access any of this (neither on mytestwa.northeurope.cloudapp.azure or somefreedomain.tk):

• admin.mytestwa.northeurope.cloudapp.azure
• play.mytestwa.northeurope.cloudapp.azure.com
• meet.mytestwa.northeurope.cloudapp.azure.com
• play.somefreedomain.tk
• ...somefreedomain.tk

Setting the wildcard DNS record for *.mytestwa.northeurope.cloudapp.azure.com to the publicly reachable IP or to the DNS name should be done from Azure Portal or from the Azure VM Linux shell?

I managed to create a free Custom domain in freenom.com somefreedomain.tk. This is what i have in freenom management panel as DNS settings.

Still don't know how to proceed, because when I try to add another record in DNS settings as * CNAME 3600 ...cloudapp.azure.com i receive the error: "Wild cards are not allowed!"

Does anyone have any idea and could help me, please?

I created an Azure resource IP Address and assigned to my Azure VM.
As can be seen in the attached picture, I also tried to Configure that Azure IP Address and Create an alias record in Azure DNS with an Azure resource DNS zone (named dns.zone somefreedomain.tk) but, still doesn't work, and my knowledge is limited regarding to DNS and subdomains stuff.

Any help or suggestions are more than welcomed!
Thank you very much!

I don't have enough reputation to put other links or images, so i'll leave the link of the initial SO question.

Azure DNS supports wildcard records. Wildcard records get returned in response to any query with a matching name, unless there's a closer match from a non-wildcard record set. Azure DNS supports wildcard record sets for all record types except NS and SOA. To create a wildcard record set, use the record set name *.

You can create such records via portal, or powershell, or cli, or api.

Reference:

• https://docs.microsoft.com/en-us/azure/dns/dns-zones-records#wildcard-records
• https://docs.microsoft.com/en-us/azure/dns/dns-operations-recordsets-portal
• https://docs.microsoft.com/en-us/azure/dns/dns-operations-recordsets
• https://docs.microsoft.com/en-us/azure/dns/dns-operations-recordsets-cli