Add a text field with the "Text" button. Paste the link into the text field, then select it and click on the hyperlink sign ("chain"). After selecting, the link is immediately inserted in the "Enter link" field. To save it, click the "Save" button.
If you want to add a hyperlink, select the word(s) that will be clickable, click the hyperlink sign and paste the link you copied in the "Enter link" field. Click "Save".
Don't forget to save your changes in the text field with the "Save" button in the lower-right corner of the field.