This is the config how to block MAM config on Android Phones.
Go to https://endpoint.microsoft.com/
Endpoint security > Conditional Access
Create new Policy
Give it a name like IOS – No MAM
Specify the group or user to apply on
Select the Office 365 app
Select Platform IOS
Add Device Filter
device.deviceOwnership -ne “Personal” -and device.deviceOwnership -ne “Company”
Set Block Access
and set it on ON
Also create a policy to Force authentication check.