Wow, thank you! I'm really glad to hear you're enjoying the asset.
Regarding the "Save Preset" feature – it's currently only available in the Unity version of the asset (which is included with your purchase). The standalone version doesn't include this feature, along with other Unity-specific tools like saving animation clips or generating an Animator Controller.
If you'd like to save a character for later, the best option in the standalone version is to take a screenshot of the Output tab, which lists all the character's specifications. That way, you can easily recreate the same character later using the same settings.