No matter where applicants are applying from, there will be an additional field under web forms. This field would ask for their confirmation for their data to be processed. 

For new web forms, you will see a default Compliance Information section to get Opt-In from Applicants. 

For existing web forms, you need to drag and drop the Compliance Information section from the Fields List. 

To customize web forms,

Go to Setup > Career Website Integration > Web forms and click on the web form you want to edit. Once edited, you will be able to preview the web form.

Note:

• Applicants will be able to view the web form as shown in the above screenshot.
  
• Applicants who do not Opt-In will not be added into the system.

Existing Candidates

For candidates who are already in your database, you could request for their Opt-In via mail.
To send out Opt-In, go to Candidates > select a candidate's record > Actions > Request GDPR Opt-In.

You can customize the Opt-In mail. Just go to Customization > Templates > GDPR Opt-In

Note: The daily mail limit is 1000.

Candidates would see a mail like this.

You can customize the two buttons in the Opt-In form. Supposing you change the content and want to change the buttons to "I Agree" and "I Disagree", just add the button names using semicolons (;).

${Candidates.GDPR Consent Form} can be changed to ${Candidates.GDPR Consent Form;I Agree;I DisAgree}

Rejecting Opt-In would place the candidate under a separate Custom View by the name "Opt-In Declined Candidates." The Opt-In information will be seen like the screenshot shown below.