Upload of zip file not working

I have an issue with uploading of a file to our squidex app. It is about a zip file that we need to upload for our client, We already have uploaded other zip files what worked greate. This zip file is 87,1MB big and every time we try to upload it, we get an error which only says that the upload fails. No other explanation.Underwater, I can see that there is a 520 error, nothing further. Also, there is still enough space for this file available according to the dashboard and the subscription we have for this app.
Do you know why this fails? Is the file to big? Some other issue?

App Name: hakron-be

Are you talking about the cloud? If yes, there is a 50MB upload limit at the moment. It is weird, that there is a 520 error code. I have never seen it.