Taobao is a mixed bag, not all of them are genuine. You must have bought it for them, so it would be best if you could figure out the sales volume after spending money. You can choose to go to Baidu Post Bar or their support station to buy albums.
Generally, signed albums are only available to those who attend the signing ceremony. Should the publicity period of their album be over?
So I don't think it is possible to sign in ...