How to share a folder in iCloud drive on a Mac running High Sierra?

If you just want to send a folder and not share the folder and work together on this folder, you could compress the folder and send the zipped folder with Mail drop. Mail Drop is supported in High Sierra, see: Add attachments to emails in Mail on Mac - Apple Support

Send large email attachments using Mail Drop

You can use Mail Drop to send files that exceed the maximum size allowed by your email account provider. Mail Drop uploads large attachments to iCloud, where they’re encrypted and stored for up to 30 days.

If you have an iCloud account and you’re signed in to iCloud when you click Send, Mail automatically sends the attachments using Mail Drop. Mail Drop attachments don’t count against your iCloud storage.

If you don’t have an iCloud account, or if you’re not signed in, Mail asks you whether to use Mail Drop (to always use Mail Drop select “Don’t ask again for this account”).

If a recipient uses Mail in OS X 10.10 or later, the attachments are included in your message. For other recipients, your message includes links for downloading the attachments, and their expiration date. 

You can turn Mail Drop on or off for an account. Choose Mail > Preferences, click Accounts, select the account, click Advanced, then select or deselect “Send large attachments with Mail Drop.”

See the Apple Support article Mail Drop limits.

You wrote - Following the process set by apple on their help links,

This is the article https://support.apple.com/en-in/guide/mac-help/mchl91854a7a/mac

Doesn't give access. in iCloud.com the process works.

It will work when iCloud Drive and desktops and documents box is checked , open www.icloud.com enter the credentials in iCloud Drive section , select the folder > file > email link to this page .

I also cannot see any iCloud folder share to me on my Mac.

From iCloud Drive , right click on folder > share > with mail , the mail compose window opens , if you want to share use link only , and Prefer using gmail account , and in To field just type your name it will automatically be saved as in address book your mail address and contacts details are already saved .

Click on try with selected server , prefer using gmail address the folder will be saved in mail compose window .

This method works when Apple ID say example1@gmail.com is signed in system preferences > iCloud and gmail address and its password is exactly the same as Apple ID and password , also in system preferences > iCloud the mail box is always checked so that it could sync with iCloud , you can use both gmail accounts and iCloud accounts and utilise their services for mails , and other applications like notes , calendars ....etc .

Note : if you are sending folder to yourself on your Mac , right click on it use get info , open the small golden lock , enter the admin password and change read and write permissions if modified https://support.apple.com/en-in/guide/mac-help/mchlp1203/mac

Suppose you used no access to the items then it could not be accessed - see this also https://support.apple.com/en-in/guide/mac-help/mchlp1038/mac

Also you are not compressing the folder .

FrancoisG_BE wrote:

Following the process set by apple on their help links, but I am not seeing on a Mac using High Sierra that I can set who can edit eat... it tries to send them the whole folder! Doesn't give access. in iCloud.com the process works. I also cannot see any iCloud folder share to me on my Mac.

iCloud Folder sharing requires macOS Catalina.

iCloud File sharing is available in macOS High Sierra.