What are the requirements for 90-day reporting with a DTV visa in Thailand?

You have your TM30 as well?

Yes, you need to do the TM47 "90-day report"

But you won't be able to do it online. The official requirements state that you must do it in person at immigration the the first time after entering in Thailand. You can then do it online each time after that.

Since most people on DTV will be leaving Thailand every 180 days, that means you'll have to do it in person every time, because they will all be your first time after entering Thailand.

You can try to do it online, but there's a 99% chance it's returned as rejected and telling you to go into the office in person.

You can try online and if rejected then go in person. You can do it until 7 days after the due date in person. The window to do it online varies by immigration office but you can never do it late online.