"Unknown Variable Container" Message

You get this message after you click Finish from the Data Generator Wizard?

Or when you attempt to use the table variable in your scripts? I would start by checking to see how your project variable was saved (is the Type = Table or DB Table? is there data in the table?):

and if you wanted to extract random data from this generated table you could do so by referencing this [TestComplete guide] -  Here is an example of how you might return a random phone number from your table:

function test() {
  var value;
  var randoRowNum = getRandomInteger(1, 2000);
  var randoPhoneNum = ProjectSuite.Variables.Var1.Item(9, randoRowNum);
  
  Log.Message("random row = " + randoRowNum + " | random phone number = " + randoPhoneNum);
}

function getRandomInteger(min, max) {
  var intMin = min;
  var intMax = max;
  if (equal(intMin, null) && equal(intMin, null)) {
    intMin = 1;
    intMax = 10;
  }
  return Math.round(Math.random()*(intMax-intMin)+intMin);
}

and here is the log returning the value from a random row in column 9 (phone#):

Since you are using Keyword tests, I would also give this a look [TestComplete reference]