Are you installing Exchange on a Domain Controller? Thats not recommended
https://learn.microsoft.com/en-us/exchange/plan-and-deploy/deployment-ref/ms-exch-setupreadiness-warninginstallexchangerolesondomaincontroller?view=exchserver-2019
For the storage supported and best practices by Exchange 2016, see:
https://learn.microsoft.com/en-us/exchange/plan-and-deploy/deployment-ref/storage-configuration?view=exchserver-2019
Mailbox Calculator:
https://techcommunity.microsoft.com/t5/exchange-team-blog/released-exchange-2013-server-role-requirements-calculator/ba-p/593922