Good news! Your i-Credit 500 meter is compatible with the Powerpal.
The pulse rate to enter into the app is 3200 and you can use the large round bracket with a tube to fit your meter. Simply fit the bracket at the top right of the meter and then gently twist your Powerpal's sensor clockwise into place.
See the image below for how everything should look once installed. Then head to https://www.powerpal.net/install and follow the instructions to complete your installation.