EACCES: permission denied when uploading a theme

I use casper theme but when I tried to upload a new theme it shows…Opera Snapshot_2020-11-26_203216_treanches.digitalpress.blog

What did I do wrong ??
I use ghost digitalpress hosted version…
How to upload alto,…and other themes please reply if you know how??

Closing as a duplicate of EACCES error when uploading or deleting a theme