cannot add custom field to content type

hello guys, i have a custom field i made with crocoblock, the name of the field is “property_desc“.

when i go to specific post and under the meta description i click on insert variable, i can then start typing proper… and it will auto complete and show me the custom field, like so: https://prnt.sc/lqLjm8u7AdRT

but when i go to yoast – search appearance – content type, and under my cpt -> meta description, it does not allow me to add the custom field: https://prnt.sc/4dOGHuTR9S4h

also if i tries to write it like this %%property_desc%% it also does not work. why?