Hi Umit,
Thanks for posting your question in this forum.
Are you able to access BIM 360 Docs via web? If you can do this then you should be able to log into the app.
Here are the two possible links:
US server: https://docs.b360.autodesk.com/
European server: http://bim360docs.eu.autodesk.com/
Do you know if your account is hosted in US or European server? This is easy to find: log into your project and check if there is an "eu" in the web address of your project: https://docs.b360.eu.autodesk.com ...
Make sure you are selecting the correct server in the start page of the app, before you log in. Use the back button of your tablet if necessary.
I hope this helps.
Cheers,
Luciane
Luciane Conceição
Product Support Specialist
Autodesk, Inc.

Please click the button "Accept as Solution" if this suggestion resolves your issue.
Luciane Conceição Taylor
Product Support Specialist
Autodesk, Inc.
Please click the button "Accept Solution" if this suggestion resolves your issue.