I assume that you use Online compiler and you have created team in Mbed Portal. In the Online compiler select the project you want to share. Select Publish and then select Fork. You can then select Publish in either your team or just your account. Then select visibility to Private. It should the be visible only your team.
Here is documentation about Publishing with Online compiler: https://os.mbed.com/docs/mbed-os/v5.15/tools/publishing-code.html
I tried to share a folder according to the site, but I got an error like “Server responded with a failure code 500 - Internal Server Error”.
What is this error and why is this error printed?