Build issue associated with .NET Framework

[lkhbgit]

I'm trying to build this on mac with .NET v7. The build is failing with the message below:

$ dotnet build BTD6\ Mod\ Manager.Lib.csproj
MSBuild version 17.5.1+f6fdcf537 for .NET
  Determining projects to restore...
  Nothing to do. None of the projects specified contain packages to restore.
/usr/local/share/dotnet/sdk/7.0.203/Microsoft.Common.CurrentVersion.targets(1229,5): error MSB3644: The reference assemblies for .NETFramework,Version=v4.7.2 were not found. To resolve this, install the Developer Pack (SDK/Targeting Pack) for this framework version or retarget your application. You can download .NET Framework Developer Packs at https://aka.ms/msbuild/developerpacks [/Users/luke/Projects/BTD6-Mod-Manager/BTD6 Mod Manager.Lib/BTD6 Mod Manager.Lib.csproj]

Build FAILED.

/usr/local/share/dotnet/sdk/7.0.203/Microsoft.Common.CurrentVersion.targets(1229,5): error MSB3644: The reference assemblies for .NETFramework,Version=v4.7.2 were not found. To resolve this, install the Developer Pack (SDK/Targeting Pack) for this framework version or retarget your application. You can download .NET Framework Developer Packs at https://aka.ms/msbuild/developerpacks [/Users/luke/Projects/BTD6-Mod-Manager/BTD6 Mod Manager.Lib/BTD6 Mod Manager.Lib.csproj]
    0 Warning(s)
    1 Error(s)

info about my .NET install is

$ dotnet --info
.NET SDK:
 Version:   7.0.203
 Commit:    5b005c19f5

Runtime Environment:
 OS Name:     Mac OS X
 OS Version:  10.15
 OS Platform: Darwin
 RID:         osx.10.15-x64
 Base Path:   /usr/local/share/dotnet/sdk/7.0.203/

Host:
  Version:      7.0.5
  Architecture: x64
  Commit:       8042d61b17

.NET SDKs installed:
  7.0.203 [/usr/local/share/dotnet/sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 7.0.5 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 7.0.5 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

Other architectures found:
  None

Environment variables:
  Not set

global.json file:
  Not found

Learn more:
  https://aka.ms/dotnet/info

Download .NET:
  https://aka.ms/dotnet/download

Any help appreciated