Birthday custome field

Dear Support!

I have created a custom birthday field in WordPress.
I would like to pass the value contained in this field to MailerLite.

I have set up the new field in MailerLite where I would like to pass this value, but I can’t find such an option in AutomatorWP to transfer this field to MailerLite when someone fills out the birthday field.

If I select “add/update subscribers” in Actions, I only find three fields there. Is there a way to find the custom MailerLite field somewhere and pass the birthday value into it?

Image: https://iili.io/J8R9kS2.png
Custom birthday field: https://stackoverflow.com/questions/62140465/add-birthday-field-to-woocommerce-my-account-and-admin-user-page

Thanks,
Neg