What's the best way to share about 120 folders with some users who may not have Dropbox accounts?

There are a few types of sharing on Dropbox, and exactly what the best thing to do will depend on your particular use case, but I'm not sure I understand exactly what the requirements are here. Do you need to be able to share files to your users, or have them send files to you, or both?

If you just need to be able to share content to people who may not have Dropbox accounts, you'd need to use "shared links". This lets you get a shared link for any file or folder in your account, so you can send that link to anyone you want. The recipient doesn't need to have a Dropbox account to see the contents. This is a read/download-only kind of sharing though; the recipient can't make changes or use this to send files to you. On the API, the flow would look like this. For each folder that you need to send out:

• Call /2/files/create_folder_v2 to create the folder, if it doesn't already exist
• Call /2/files/upload to upload file(s) to the folder, or use any other means of uploading to your account, e.g., via the web site, desktop client, etc. like you mentioned
• Call /2/sharing/create_shared_link_with_settings to create a shared link for the folder, or /2/sharing/list_shared_links to retrieve an existing shared link. (You only need to do this once per folder; the shared link for a folder doesn't change when you add or update the contents of the folder. Just don't delete the folder or revoke the shared link itself.)
• Send the shared link to your recipient via whatever means you use (email, etc.).

If you do need them to be able to send files to you, still without them needing to have Dropbox accounts, then "file requests" would be the best option. There isn't a way to change that filename behavior though. You can use /2/file_requests/create to programmatically create file requests.

And if you need both, you could set up file requests and shared links for the same folders, that way, they could both see the contents and add more.

By the way, those are links to the documentation for the HTTPS endpoints themselves, but we recommend using one of the official SDKs if possible. Those have corresponding native methods for the HTTPS endpoints.