Hi Rishary,
the maximum size for avatars that you upload yourself is currently 130x130 pixel. If you use an avatar from an online source the maximum size is 65x65. There is no file size limit in place.
I can see that you tried to upload an avatar but it has 0kB. Maybe the upload was interrupted or some adblocker or script blocker interrupted something?
Please try again! If it still doesn't work you can send me your avatar and I'll put it in place for you. :3
PS: I'll move this topic into "Forum Issues" as it belongs there. Don't be alarmed. :3