Azure Databricks deployment- unable to create Private Subnet CIDR Range

In Azure, I have a virtual network (vNET) with following settings:

 Address space: 10.200.0.0/20
 subnet: 10.200.0.0/24

Inside the above vNET, I am trying to deploy an Azure Databricks with the following Network settings:

Public Subnet CIDR Range: 10.200.15.0/20
Private Subnet CIDR Range: 10.200.15.1/24

But on the Private Subnet CIDR Range above I get the following error:

Public and private subnet ranges must be valid and non-conflicting

Question: What I may be doing wrong, and how can I resolve the above error?

Remarks:

• I have tried various variations of 10.200.15.1/24(e.g. 10.200.15.0/24, 10.200.15.255/24 etc.) but I keep getting the same error. I am sure there must be a correct Private Subnet CIDR Range that I am not using.
• I noticed people have pointed out to some online tool such as the following, but I am not a networking expert, and I am not sure how exactly I can use these tools to get correct Private Subnet CIDR Range. CIRD Calculator, Subnet Calculator for IPV4, and IP Calculator.

UPDATE I'm following this tutorial from Azure team. When I tried the following settings, I get the error shown below:

Subnet range is not within the Virtual Network range

The CIDR tool I like to use is https://www.ipaddressguide.com/cidr.

Your public subnet 10.200.15.0/20 has a starting IP of 10.200.0.0 and ends with 10.200.15.255.

Your private subnet 10.200.15.1/24 is not even valid. You can check this SO answer as to why that is.

Change the private subnet to 10.200.14.0/24. Keep the public subnet as is. These are not overlapping and completely valid. 10.200.16.0/24 is outside the ip range of your vnet, so you can't use that.