@ffalcitelli you cannot call rules or transforms in Workflow.
For your usecase you can use the Define Variable Operator - SailPoint Identity Services.
This operator can assist you with your use case. Using it, you can:
- Concatenate your different attributes coming from your forms.
- Use the replace function to remove spaces.
However, I don’t see a “to lowercase” operator available. You might want to check if you can use the replace function with regex syntax to achieve that.