I have sweaty hands and feet and have always had stinky feet. Washable shoes are a game changer. Throw away her socks and shoes and get new washable ones. Seriously, don't try to salvage them, just start fresh. Wash shoes in vinegar or enzyme cleaner as soon as they start to smell, rotate shoes, and get shoe liners like these:
https://www.amazon.com/FLAT-SOCKS-Moisture-wicking-Breathable-Explosion/dp/B0BVGKND5Y/ref=pd_day0fbt_softlines_d_sccl_1/136-1932835-5739445?pd_rd_w=h3hXU&content-id=amzn1.sym.2279ea12-5619-4202-8979-7016a550b5be&pf_rd_p=2279ea12-5619-4202-8979-7016a550b5be&pf_rd_r=HW02Y60BW8ZZEFYP10X6&pd_rd_wg=nl9vd&pd_rd_r=db200db2-0902-4392-98ff-145193dda8e0&pd_rd_i=B0BVGKND5Y&psc=1. I use these exact liners in winter boots (leather only, no plastic shoes) and dress shoes that can't be washed.
For her stinky feet, scrub them thoroughly with antibacterial soap, and soak in a (diluted) vinegar bath until they don't smell at all. If they smell, there's still bacterial that will get into her new shoes and you'll be back to square one. Powders and deodorants won't fix the problem because you just need to kill the bacteria and keep it from recolonizing. I sometimes use regular spray deodorant on my feet when I can't wear socks, but that's not something you want to do every day. Use antibacterial soap in the bath and teach her to clean her feet thoroughly, including between her toes. And if she's mature enough, get her real pedicures to keep the outer layers of dead skin from building up. And don't put stinky feet in shoes. Wash, or have her wash, her feet BEFORE she puts her shoes on.