If you want to add a file to a text editor,  Click the (Link) icon to proceed.

https://support.coursemos.kr/attachment/view/602/clipboard.png

(1) Type the text, then drag the text to select it.

(2) Click the 'Link' icon.

(3) Click the [Browse Repositories] button on create link to locate and select the file under File Picker > Attachment.

https://www.learnus.org/pluginfile.php/4632352/mod_ubboard/article/799651/스크린샷 2022-08-18 오전 11.33.38.png