Hi philippa166,
Thanks for using Apple Support Communities. We understand you want to share some iCloud content. We're happy to provide some information to help. When trying to share make sure you're using the steps here:
1. In iCloud Drive on iCloud.com, select the file or folder you want to share, then click 
.
2. Click Share Options, then choose who can access the file or folder, who can make changes, and if participants can add people to the file or folder.
3. Choose how you want to share the link:
• Email: Click Share. In the email window that appears, invite participants by adding their email addresses or phone numbers in the To field. Make any additional edits to the email, then click Send. The email option is only available when you have iCloud Mail turned on.
• Copy Link: After you select Copy Link, a text box appears. Add the email addresses or phone numbers of your participants. Click Share. A new window appears with the link for your file. Copy the link and send it.
When you share a folder, only the participants can view the files in the shared folder. To invite more people to access the files, you must change the settings of the shared folder. You can’t select an individual file or folder within the shared folder and add participants to it.
See more about those steps here: Share files and folders in iCloud Drive on iCloud.com - Apple Support
If those are the steps you're using and this continues, let us know if you're able to share other content without issue. We'll go from there.
Thanks.
