I have a relatively weak device so I usually use renderfarms to render my scenes. The problem is that I can't use the the external frames in blender compositing. A workaround I use is that I render the scene at a lower quality and composite it before uploading it to the renderfarm. The problem is in highly details scenes the lower quality renders makes it hard to perfect the compositing to my liking for the small details.
What I want to do is to save the externally rendered frames in the default render cache folder so that blender would detect it in compositing.
Some solutions suggested that I go to Preferences > File Paths > Render Cache, but that field is blank for me so I don't get useful information from this.