1)

Click on the "+" icon

2)

Click on the "Tooltip Guide"

3)

Enter a name for the Tooltip

4)

Add a Rule

5)

Click on "Submit"

6)

Click on "Add Step"

7)

Select "Validation"

8)

Select the element on which you want the tooltip to work

9)

Select "Validation type" from here 

10)

Select "Regular expression"

Regular expressions (shortened as "regex") are special strings representing a pattern to be matched in a search operation

11)

Enter the regex and a message for sake of displaying on tooltip and save it

12)

Ensure that the parent folder is published where you have created the tooltip guide

13)

When your entries do not match with the regex, the validation message will appear like this