I have a Hybrid Office365/Exchange 2010 configuration. If I create a new mailbox on Exchange 2010 (onpremises) my autodiscover works fine inside my organization. If I configure this onpremises account on my Android phone its works fine (changing mail server from outlook.office365.com to mail.mydomain.com)
Outside my organization when I configure my Outlook 2016 (VLSC version, not Click to run version) and put my email and credentials a Office365 window pop-ups and my credentials are not accepted.
My question: all new onpremises created mailbox (exchange 2010) need to sync to Office365 cloud too (even without license)??