Yes you can do this. First, in your OneDrive you need to create the folder, then share it with edit permission.
You send the share link to your customer, and they need to have their own OneDrive account, which they can add your folder to. See this article:
https://support.office.com/en-gb/ar...cd8-bd09-ee3f9bfc1504?ui=en-US&rs=en-GB&ad=GB
Then any files that are put into that folder are available to everyone who you have sent the link. The storage in that folder counts against your quota but not against your customers' quotas.
If you do not want your customers seeing each others' files then you will need to create individual folders for each customer and share them individually, but the process is the same - each customer adds the shared folder to their own OneDrive account.
Hope that's helpful.