couldn't start Photos app with a photo library in external hard drive

"Photos was unable to make a copy of your library before preparing it. Photos does not have the necessary permissions..."

The pop-up menu allow me to read some solution in this site (If Photos can’t copy or create a library - Apple Support), but it only contains with default location in the picture folder. I've been using my photo library in external driver which I made as one for timemachine, and the terminal solution didn't work for me('couldn't find location' after entering passwords). Please help.