DL arrives terminal T1, scoot leaves from T2, the terminals t3-T1-T2 are joined (T4 is separate). Aerotel is in T1 and about 15 min walk to Scoot. Not sure if you can use transit for Scoot as it is LCC, for normal airlines you can easily stay in transit even overnight. Scoot seems to restrict transit to SQ fliights (not surprising as owned by SQ). Worst case you may need to check in landside but try online check-in with Scoot first