According to the WYGWAM Installing and Updating page, WYGWAM requires ExpressionEngine 2.4 or late.
However, if you are using both WYGWAM 3.2.1 and Assets 2.2.2 (may be the same for older versions) and you are running an EE version less than 2.6, you are likely going to get the following error when attempting to access any of the Editor Configurations within WYGWAM's settings:
Call to undefined function ee() in /PATH/TO/INSTALL/DIR/system/expressionengine/third_party/wygwam/mcp.wygwam.php on line 139