Are you referring to the Samsung Care+ promotion when ordering the Fold⁴ @beetle69 ?
Going from the information on the buying page from Samsung this needed to be added at before checking out.
See my previous reply here to which I offer some help. > https://eu.community.samsung.com/t5/galaxy-z-fold-z-flip/samsung-care.
Registering the phone via your Samsung Members App helps log your information on Samsungs database if support is ever needed at a Samsung Service Centre or Samsung Experience Store.
It won't add the promotional Samsung Care +
I wish you all the best. 
