Small business management - QR codes and scanned documents mess

I apologize if the thread title is a bit confusing, but my brain is fried, and this is the best I could do. I need your help with a little family adventure.

My uncle's small business (car stuff - spare parts, batteries, accessories) is currently a bit of a delightful mess - we're talking tons of important documents scattered in random boxes. It's like a treasure hunt but without the treasure. Only me pulling my hair when I end up not finding the paper I really need.

I've taken it upon myself (to try) to save the day, and I want to scan and organize all these documents. Any suggestions for software to help me with this epic endeavor? Can the files be stored in Windows folders to make it easier for him to find his way around? Basically, what I don't want is an expensive piece of software with a complex system in place. I looked into something called M-Files, looks impressive, but definitely not for a small business on a budget with not really tech-savvy owner. So, something of that type but simpler and cheaper, to put it that way.

But, of course, there's more. He asked me to help with his inventory management. Rumor has it, that his competitor (and nemesis) started using QR codes so naturally - now we want them too. Joke aside, I think it's a great idea, but I'm running into a bit of a pickle. Those free QR code generators I found either limit the number of scans or have codes that expire faster than a carton of milk in a heatwave.

Ok, this is turning into a saga, sorry. If anyone knows of good document storage software or a free reliable QR code generator - please share so that I can wrap this up and continue with my life, far, far away from car parts.