Hey @Grisu112NRW welcome to the Nextcloud community 
please be clear, what are you trying to do?
it may help if you add a screenie or two so we can understand your issue.
so, you’re trying to create an external link to a file/folder for an external non-nextcloud user right?
- select external share
- add a share by clicking “+”
- configure the share by clicking “…”
- copy the share link
- send the share link by mail/messenger/etc…
