An update to a long useful introduction to Ham DMR.
Amateur Radio Guide to Digital Mobile Radio 2nd Edition

Step 1 - Sign up for a Radio ID number.
https://www.radioid.net
Given that the process takes time, go ahead and sign up for a radio ID number before your new DMR radio shows up in the mail. In general, even if you have more than one radio and a hotspot, you can get by with just the one number. But, you do need the one unique in the whole world number if you are going to operate on one of the world-wide DMR networks. Click on register and follow the instructions. They will ask you to submit a scan of your ham license.
FAQ #1: Why do they need a scan of the "Official Copy" of my ham license? Answer: Because anybody can download a Reference Copy of your ham license. Only the FRN owner (you) can download and print an Official Copy.