shared anki not opening

hello , I am a new anki user and I have downloaded a shared deck , it was working fine until it started to show this :

Back template has a problem:
Found ‘⁨{{#Lecture Notes}}⁩’, but there is no field called ‘⁨Lecture Notes⁩’
More information

You need to edit your card and correct the field name in your back template. Probably it’s {{Lecture Notes}}⁩, not {{#Lecture Notes}}⁩

I tried but it keeps saying this I don’t get it

Card template ⁨1⁩ in notetype ‘⁨Cloze-21ff7⁩’ has a problem.
See the preview for more information.

You need to provide more info: what does it say when you preview the card? Can you post a screenshot of your templates, or a link to your shared deck?

Please see Card template has a problem - Frequently Asked Questions