Hi there Saransh Dabas
I guess its due to resource availability and limitations in the free trial version. The "Standard_DS3_v2" VM might not be available in your region or under your current subscription limits, which is why you're being assigned a different VM, like "Standard_D2as_V4." Since you're using the free trial, you may be hitting resource quotas, or certain VMs might not be accessible based on availability in your region.
I suggest you checking your Azure subscription's resource limits and trying a different VM or region or upgrade your subscription.
If this helps kindly accept the answer thanks much.