Hi jesits,
Thank you for participating in the Apple Support Communities. It looks like you came from the following support article: How to add a Legacy Contact for your Apple ID - Apple Support
If you are unable to add a Legacy Contact, here are steps that may be useful:
1. Restart your iPhone to see if the issue persists: Restart your iPhone - Apple Support
2. Update your iPhone to rule out the older software: Update your iPhone or iPad - Apple Support
3. Once you have done step 1 and 2, now you can try the steps here to see if they help: How to add a Legacy Contact for your Apple ID - Apple Support
4. If you need further support, reach out to Apple Support here: Contact - Official Apple Support
Have a great day.