Atkins Graduate Architect interview questions

Filled a lengthy application form on LinkedIn. Followed by an online aptitude test. After clearing that we were called to the office for 3 other rounds: Group discussion, technical interview and HR interview. Received a call after 5 days to give a Revit tool test. 20 days later I got an offer email and was asked to send a set of documents. It's been over 10 days since, yet to receive a physical offer letter. It's a long and tedious process.