These are Donna's Rollups

There are no Apex Classes that start with rollup_

You've got the DLRS tool installed but there is no Lightning app for it. And no way to "upgrade" it to lightning.

There's the tab.

Switch to Classic...

And this is what I get when I click Create New

By Comparison, here's the Lightning Tab in one of my other clients' Salesforce instance.

And when I click: Create new, I can see all the DLRS rollups that I created.