We have requirement to add customer aspx and its js file to SharePoint online but we dont have SharePoint Designer, if we upload the files to site assets and try to open, it is getting downloaded instead of rendering.
As per this post - Sharepoint downloads aspx file instead of rendering it
we tried to upload it to site pages but it is not allowing us to upload the file, it is not allowing us with below error message
Is there any way to upload the files without SharePoint designer ? User is only site member, user dont have full control on SharePoint site.