Hi!
Photoscape is a windows only application and the snap package you would like to install, should be then a pre-configured wine environment running Photoscape.
I would suggest to install it manually:
Install wine
pamac install wine
Create a wine bottle:
mkdir ~/Photoscape
WINEPREFIX=~/Photoscape WINEARCH=win32 wineboot
Install Photoscape
WINEPREFIX=~/Photoscape WINEARCH=win32 wine PhotoScapeSetup_V3.7.exe
After following the setup, there must be a shortcut at the category wine of the startmenu.
https://appdb.winehq.org/objectManager.php?sClass=application&iId=7854