1)

Click the floating plus icon in the lower right of a folder

2)

Select "Tooltip Guide"

3)

Enter a name for this tooltip

Add a URL rule where you want to place the tooltip 

4)

Select "Validation" from the tooltip types

5)

Select a validation type from here

Capture the element where you want to apply validation

6)

As we have shown the captured element as an email field, we will select "Email address format"

7)

Enter a message for the users to follow

Select a suitable position

Click "Save"

8)

Publish this tooltip and it's respective parent folders

9)

As soon as you will start typing something, a validation message will appear

10)

These are simple validation types -

• Mandatory field - We just have to let the user know that he can not skip this field
• Numeric field - Used where we need users to enter numbers
• Date format - Used where we need users to enter or select date
• Time format - Used where we need users to enter or select time
• Email address format - Used where we need users to enter their email address
• Web address format - Used where we need users to enter a web address
• Phone number format - Used where users need to enter their phone number 

11)

You can learn about using these validation types from here