PDF and image error

I cannot add a valid PDF of less than 700 kB in size - uploading error all the time. I ve tried different browser, clearing my cookies, even incognito mode.
Also, in editing of a flashcard, there’s an error whenever I try to add an image. - Something went wrong. Please try again.

I need to add images to my flashcards, it s crucial for my studying.

Pls help