You or your client get their Stimulus amount info at this link:

https://www.irs.gov/payments/view-your-tax-account

Or get it by paper. I earlier posted this link to an account transcript image, which you can get for them or they can get for themselves. It shows how the listings appear:

https://www.irsmind.com/irs-notices/irs-transcripts-now-provide-stimulus-payment-information/