error E2202: Required package 'IntraWeb_15_D12' not found

In step 4 in the install.txt to the TMS IntraWeb Component Pack Pro, version 5.9.4.0, when running msbuild iw15tmsdedxe15upd.dproj, I get the follwing error: error E2202: Required package 'IntraWeb_15_D12'.

Can you please make sure you have correctly installed IntraWeb 15 before attempting to install TMS IntraWeb Component Pack in Delphi 12?