Copyright and bundling the installer

Hi, I wrote a WIX bootstrapper to download "postgresql-9.6.13-1-windows-x64.exe" / "pgadmin4-4.6-x86.exe" and to install it from the bootstrapper, and it looks like this:

However, when I ran the bootstrapper, it failed with the following errors during postgresql exe download (the same error also occurred for pgadmin4 exe):

Prompt for source of package: PostGres, payload: PostGres, path: C:\3rd_party\\postgresql-9.6.13-1-windows-x64.exe
Acquiring package: PostGres, payload: PostGres, download from: https://www.enterprisedb.com/thank-you-downloading-postgresql?anid=1256629
Error 0x800b0003: Failed authenticode verification of payload: C:\ProgramData\Package Cache\.unverified\PostGres
Error 0x800b0003: Failed to verify signature of payload: PostGres
Failed to verify payload: PostGres at path: C:\ProgramData\Package Cache\.unverified\PostGres, error: 0x800b0003. Deleting file.
Error 0x800b0003: Failed to cache payload: PostGres
Failed to cache payload: PostGres from working path: C:\Users\petronius\AppData\Local\Temp\{36b05203-ecc5-4f24-a06c-a11f0dedc47c}\PostGres, error: 0x800b0003.
Error 0x800b0003: Failed while caching, aborting execution.

Here is how I authored the bootstrapper using WIX:

<Chain ...>
<ExePackage Id="PostGres" PerMachine="yes" Vital="yes" Permanent="yes" Compressed="no"
InstallCommand="-mode unattended --prefix &quot;C:\Program Files\PostgreSQL\pg96&quot; "
DetectCondition="POSTGRESQL_96"
DownloadUrl="https://www.enterprisedb.com/thank-you-downloading-postgresql?anid=1256629"
Name="$(var.3rd_party_dir)\postgresql-9.6.13-1-windows-x64.exe">
<RemotePayload
CertificatePublicKey="D1432F6E0E3882BFB2F9E78CCDE27F68392752C7"
CertificateThumbprint="D0FF74B01ABA3DBB314C9A59CB64C39569F3366E"
Description="PostgreSQL 9.6" Hash="C591BE8E06D7081969A83E26EE6BCACDA59AC5BF"
ProductName="PostgreSQL"
Size="160493264"
Version="9.6.0.0" />
</ExePackage>

<RollbackBoundary/>

<ExePackage Id="PgAdmin4" PerMachine="yes" Vital="yes" Permanent="yes" Compressed="no"
InstallCommand="/SILENT /NORESTART"
DetectCondition="PGADMIN_4_PATH"
DownloadUrl="https://www.postgresql.org/ftp/pgadmin/pgadmin4/v4.6/windows/"
Name="$(var.3rd_party_Dir)\pgadmin4-4.6-x86.exe">
<RemotePayload
CertificatePublicKey="D1432F6E0E3882BFB2F9E78CCDE27F68392752C7"
CertificateThumbprint="D0FF74B01ABA3DBB314C9A59CB64C39569F3366E"
Description="pgAdmin 4 Setup"
Hash="0BDFC84AB1D7516C2EBE436C405341AB87D8ED65"
ProductName="pgAdmin 4"
Size="72386528"
Version="0.0.0.0" />
</ExePackage>
<MsiPackage .../>
</Chain>

If I do not download but statically include those EXE's to the bundle, it works fine.
I've been search for the cause for a couple days but no luck. Did anyone approach this way and successfully downloaded and continued to install?

Another question:
Due to this error, I am think to embed those EXE's to the bootstrapper, but I do not know if it is against licensing policy.
Is it okay to do it?

Thanks.