RIDEM is where you go to sign up for the test and I believe get your manuals. There’s a core manual for the basics and a category manual for the specific use of your license You’re likely looking for 3b. The test is done online and from what I understand it’s very strictly closed book, it tracks your eye and head movements and will fail you if you look away for too long.

University of Rhode Island has a two hour or so primer on zoom. It’s $175 but hopefully your employer will cover it. Nonetheless, they go over exactly what’s on the test so it is helpful.

Edit to add more.

As far as I know there’s no one and done anymore. When I did it 15 years ago I went down to URI and took a class in the AM and wrote the test in the afternoon. Everything I mentioned is just based on coworkers currently getting theirs.