Create modern team site collection using CreateAsync

[Dipali-arup]

I'm using PnP.Framwork 1.14.0 and .Net 6.0. I'm trying to create modern team site as per below code but it fails at CreateSiteAsync method call. Could anyone help me understand why it would be the case?

// Get a reference to the ClientContext of CSOM
AuthenticationManager auth = new AuthenticationManager(SPAdminUserName, securePassword);

using (ClientContext context = await auth.GetContextAsync(adminUrl))
{
TeamSiteCollectionCreationInformation modernteamSiteInfo = new TeamSiteCollectionCreationInformation
{
Alias = "TestSite",
DisplayName = "TestSite",
Description = "TestSites",
Owners = ownersList,
IsPublic = true,
Classification = "General"
};

var createModernSite = await context.CreateSiteAsync(modernteamSiteInfo);
if (createModernSite != null)
	success = true;

}