Setting up approvals in MIM 2016. There is a well known bug in FIM 2010 that approval workflows will not run on SP 2013. The work around is to edit the XOML file fo the workflow and change the dotnet version to 3.5. Here is a blog post that explains what to do. Well this issue has not been fixed in MIM 2016, I still have to do this workaround. It also means that you have to use XOML file to make changes to your approval workflows similar to the way you use xml files to update your RCDC. or you have to remember to go to the advanced properties of the workflow after a change to the properties to change the dotnet back to 3.5. I would recommend using the xoml files and use Powershell to script all updates. So many advantages of that.
A couple of things to note about setting up approvals using the OOTB approval template. You got to have email connection to the FIM Portal, so some SMTP gateway configured else your approvals will not complete.
I want to do an approval in an action workflow. Go to All resources, Activity Information Configuration, click on Approval and in extended attributes check Action. Do IISreset to see approval in the action workflow.