Could not load file or assembly 'BouncyCastle.Crypto, Version=1.8.1.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies

I am trying to integrate the Walmart .NET SDK into a .NET 4.61 MVC 5 app. Using NuGet, I added a reference to BouncyCastle.Crypto 1.8.1.0.

The SDK uses .NET Standard 1.3 and it references BouncyCastle.Crypto 1.8.1.3:

https://github.com/walmartlabs/partnerapi_sdk_dotnet

1.8.1.3 is not available for .NET 4.61.

{"Could not load file or assembly 'BouncyCastle.Crypto, Version=1.8.1.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)":"BouncyCastle.Crypto, Version=1.8.1.0, Culture=neutral, PublicKeyToken=null"}

=== Pre-bind state information ===
LOG: DisplayName = BouncyCastle.Crypto, Version=1.8.1.0, Culture=neutral, PublicKeyToken=null
 (Fully-specified)
LOG: Appbase = file:///C:/Users/example_user/Source/Workspaces/CCC/Test/example_app.Test.DataAccessUnitTest/bin/Debug
LOG: Initial PrivatePath = NULL
Calling assembly : Walmart.Sdk.Base, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null.
===
LOG: This bind starts in default load context.
LOG: Using application configuration file: C:\Users\example_user\Source\Workspaces\CCC\Test\example_app.Test.DataAccessUnitTest\bin\Debug\example_app.Test.DataAccessUnitTest.dll.config
LOG: Using host configuration file: 
LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\v4.0.30319\config\machine.config.
LOG: Policy not being applied to reference at this time (private, custom, partial, or location-based assembly bind).
LOG: Attempting download of new URL file:///C:/Users/example_user/Source/Workspaces/CCC/Test/example_app.Test.DataAccessUnitTest/bin/Debug/BouncyCastle.Crypto.DLL.
LOG: Attempting download of new URL file:///C:/Users/example_user/Source/Workspaces/CCC/Test/example_app.Test.DataAccessUnitTest/bin/Debug/BouncyCastle.Crypto/BouncyCastle.Crypto.DLL.
LOG: Attempting download of new URL file:///C:/Users/example_user/Source/Workspaces/CCC/Test/example_app.Test.DataAccessUnitTest/bin/Debug/BouncyCastle.Crypto.EXE.
LOG: Attempting download of new URL file:///C:/Users/example_user/Source/Workspaces/CCC/Test/example_app.Test.DataAccessUnitTest/bin/Debug/BouncyCastle.Crypto/BouncyCastle.Crypto.EXE.

I had to use the .NET 46 solution. The Walmart.Sdk.Base assembly is built on .NET Standard 1.3. I needed to reference the one for .NET 4.6.