Solus does not use deb packages. So you're better off using the flatpak.
First time using flatpaks you'll need to run
sudo eopkg install flatpak xdg-desktop-portal-gtk
sudo flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
Install WPS Office:
flatpak install com.wps.Office