Hello miracle292,
Thanks for using Apple Support Communities.
We understand you are experiencing some issues with downloading files using Safari. We are happy to help look in to this with you.
To start, we would like to check to see if Safari is using any plug-ins and might be interfering with your downloads. Take a look at how to check for that here:
If you need to disable or block a Safari plug-in on Mac
If there aren't any plug-ins enabled, or disabling them did not help, we would like to ask some questions to get a better understanding of what might be happening.
1.) How is your Mac connected to the internet? Are you using a Wi-Fi connection or ethernet?
2.) Are you able to download files if you use a different internet browser, such as Google Chrome or Firefox?
3.) When did you first notice this behavior start? Was it after any sort of change, update, or new app download?
Let us know how it goes and the answers to those questions if you are still experiencing issues.
Best Regards.