How do I get workplace accommodations and how does it work?

Hello, I (21, ftm) am trying to figure out how this whole accommodations work, since I am going to try to get a job that isn't just retail. I been having so many questions and doubts, yet when I try to look it up it too vauge for me to understand.

This all started since a service that been trying to "help" (i say help, since they didn't and I was doing better without them) find a job. They said that they need to assess me with my work ablites and what I need. Even though I worked retail and was able to handle a job just fine. I even told them this but they didn't belive me. They had me do some job "training" thing, so they can 'teach" me how a job works. I try to stop these services since I felt like I was doing free labor. Yet, my mother over ruled my choice.

Saying something on the lines of "we have to assess you so we know what you need". Like is that how getting accommodations work? I just need some help, since I don't want a random 'service" I don't want to give people the wrong infomation. Since I know my own short commings, but people tend to see me as "shy and defenseless". Only because I have a hard time sticking up for myself when I feel like my mother is around.

Like do I get accommodations, like is this service the only way to help me or is there another way to get accommodations.