There is no legal requirement for tenants to sign the document – it’s good practice, but not a requirement. From your perspective - as long as you can evidence that prescribed information (PI) has been served to the tenant – you’ve done what you’re required to do. And audit trail will evidence that it has been sent to tenants.
To encourage tenants to sign prescribed information, we’ve added wording to the email that reads as “Signing this will help avoid disputes over the return of your deposit, so you can get your money back faster at the end of your tenancy.”. Tenants will also get daily reminders to sign this document. Finally, we will be monitoring the success rate of getting PI signed, and will think of ways to improve it if it is low.