I have volunteered on the signup phone banks and at the city-run distribution sites. It's actually incredibly easy for the volunteers. In part because they overstaff on volunteers, so individual jobs become "you are checking people off a list" and "you are welcoming people at the door and pointing them to a chair." Each task I have done as a volunteers is easily explained in minutes.
My city's volunteer corps partnered with 311 to handle the registration. It worked very well because they basically just piggy-backed off 311's system already in place. And 311 handled the initial start, before it was streamlined and handed off to volunteers as the rollout increased. People can register by calling 311 or going to the 311 website. For volunteering, it was basically just simple data entry. You are reading out the form people would be using on the website. What's your name, date of birth, address etc. Spelling errors are not super important. (That's one of the volunteer jobs at the distribution center - having people check over their forms for any errors.) The computer system automatically determines their eligibility based on age or their answers to various other questions, and then the software pulls up the available dates and you schedule them. If there were no dates available, they automatically go on a waitlist for a call or email when more appointments open. If they are not eligible, they automatically go on a waitlist for when the system determines they are eligible.
For the data entry, there was a training session for the LINKS system, but really - so so easy. I hear from so many people about how nice the 311 vaccine operators are when they call, but it makes sense. Volunteers work 4.5 hour shifts with little to no stress. It's very easy to stay upbeat and helpful when the system isn't overburdened.
#BidenHarris2020 “It’s easier to be a parent this morning. It’s easier to be a dad. It’s easier to tell your kids character matters. It matters. Telling the truth matters. Being a good person matters.”