There is an issue with your Electronic Arts account CANT SUBSCRIBE.

@Fumiirou1 

You need to reset the password on the linked EA account that account has the persona Engeis (not lViviMortel that your posting on now) that EA account uses a different gmail email then what is on your swtor account

use the following link to reset the password https://signin.ea.com/p/web2/resetPassword  then login on that EA account to fix the swtor account for purchasing

for future purchases, use incognito mode on chrome initially if you purchase on swtor.com to be sure browser cache and cookies is cleared