Hello,
I think that, judging from your previous thread, you are a brand new player on a new server. If this is the case, this is what is going on.

The "daily sign in" requirement is triggered for many events when you actually click the calendar date in the Daily Sign In tab of the Benefits Hall interface. If you have clicked today's date to sign in *before* the activation of any events or interfaces that require it, you will be unable to get it (again) for that day. This is because you have already triggered it, and it's not about "being logged in" but rather the act of signing on through that interface. This is generally true for most events/interfaces in the game (myoboku trial is a notable exception for some reason). Unfortunately, this means that you will miss today's credit for daily sign in, but you will be able to get it moving forward, as long as you don't trigger any additional new events after you have signed in for the day.

As for the image uploads, there is a hidden size limit of about 2MB for images. If you go over this size the upload will fail. I would recommend making the client smaller when taking your screenshots, or compressing the image or changing its filetype to reduce its overall size. Cropping it is generally not recommended since often this will remove information you are not aware is important, but that we need to process the request. Also, do be mindful of sensitive information in your images, such as your email address at the top of the screen.

Hopefully this helps, thanks and have a great day!

Okay, thanks for the heads up

No problem!

Oh, it is also worth pointing out that this issue can happen with events on thursdays. If we have an event like summer memories and you are in the UK/HK region, you can "log in" before the events go live, meaning you can potentially see this error once a week when events start. You'll want to check to see which events are available and hold off logging in if this is important to you.
Have a great day!