how to solve this error? Error 205??

This is caused by a permissions issues on your system. 

Your hard drive needs administrative permissions to read/write/edit files on your system.

Windows: https://answers.microsoft.com/windows/forum/all/administrator-permission-issues-on-window-10/207ef1f7-19e6-44a6-87d2-db2d05c36515

If your school/work computer does not afford you administrative permissions, contact your IT dept for assistance.

This article should help you out: https://community.adobe.com/t5/indesign-discussions/keep-getting-an-error-code-205-when-launching-indesign-2019-and-2020/td-p/10737948