I think most neurotypical people would consider working as a cashier to be a job that is not particularly hard to learn (although they certainly wouldn’t be great at it straight away), but difficult in terms of stress and obnoxious customers and managers.
Am I right in saying neurotypical people tend to have less empathy? Sometimes they may underestimate the difficulty in learning the job, even if they had to learn the job not too long ago. They can have a curious “amnesia” about the difficulties they had.
I had a few retail jobs. I was decent enough at unpacking boxes, stocking shelves and that kind of thing. I got on well with the more laid back customers. Being a cashier though? I was probably in the top ten worst cashiers in human history.
One suggestion would be to ask yourself, can you live with it if the girl training you thinks you’re not very smart, for now (I don’t think you’re not smart, I’m just asking can you live with the possibility of one person thinking of you that way. I’m also not saying that she thinks of you that way either)? Maybe you could keep pen and paper handy when she’s giving you instructions, ask her to slow down and things like that.
Also when you’re not working, you could spend a little time thinking about what you recently learned on the job, and also write it down if you can.
It’s curious that training tends to be so bad in these retail jobs.. And that the managers are often so rubbish (okay, I know it’s because they have managers above them breathing down their necks or whatever)..
Anyway, I’m sure you can be a good cashier, you may just need to learn things your own way. As an ADHDer, you probably have more creativity than most. You can probably come up with good ideas to help you. I see there are videos about working as a cashier on YouTube, but I haven’t watched them so I can’t vouch for their quality.