Hi @Sburel,
Just saw your post now, sorry for late reply.
For any model evaluation on test set, you can use Model Comparison platform (on test rows only) : simply select your XGBoost prediction formula as Y Predictor and you'll get Rsquare, RASE (=RMSE) and Average Absolute Error calculated automatically. Some other metrics like Correlation can be calculated with other platform : for Correlation, you can use Multivariate platform with the predicted response and measured response to see the actual vs. predicted plot (also available in Model Comparison by default) as well as correlation value.
Hope this answer will help you or other members,
Victor GUILLER
"It is not unusual for a well-designed experiment to analyze itself" (Box, Hunter and Hunter)