Decipher the message UTZWZKZLZVGVBWB by using the Auto key cipher method with $15$ as the key. Please include the following results:

$[1]$ The values of the corresponding cipher text $[4$ points$].$

$[2]$ The value of the corresponding key stream $[6$ points$].$

$[3]$ The value of the corresponding plain text $[6$ poin and then

$[4]$ The final result of the corresponding plain text $[4$ points$].$