How can I convert an array in JSON to a data type that my controller can handle

I have an API that is using .NET Core 3.1 Entity Framework.

I am getting data from a client side POST event that contains JSON with an array that looks like this:

  "SpaceTrainees": [
    "Pilot",
    "Commander",
    "Grunt"
  ] 

My Controller that is handling the post event is throwing an error when it hits that array:

I am getting this error:

 "$.SpaceTrainees[0]": [
            "The JSON value could not be converted to System.Collections.Generic.List`1[System.Int64]. Path: $.SpaceTrainees[0] | LineNumber: 2 | BytePositionInLine: 21."

The code block in my controller that throws the error:

[HttpPost]
public async Task<ActionResult> ProcessRecruit([FromBody] CreateCadet data)     
{
...

    foreach (var traineeId in data.SpaceTrainees)
    { ... }

    Return Ok();
}

--> where data.SpaceTrainees is of List

The model for CreateCadet contains a property:

public List<long> SpaceTrainees {get; set; }

Is there a way to make this work?

Thanks!