It says hplip-gui command does not exist.
sudo apt install -y hplip hplip-gui
[sudo] password for raymond:
Reading package lists... Done
Building dependency tree
Reading state information... Done
hplip is already the newest version (3.20.3+dfsg0-2).
hplip set to manually installed.
The following packages were automatically installed and are no longer required:
chromium-codecs-ffmpeg-extra dctrl-tools dkms fonts-wine glib-networking:i386 gstreamer1.0-plugins-base:i386 gstreamer1.0-plugins-good:i386 gstreamer1.0-vaapi
gstreamer1.0-x:i386 heif-gdk-pixbuf intel-media-va-driver:i386 libaa1:i386 libaom0:i386 libapparmor1:i386 libasn1-8-heimdal:i386 libasound2:i386 libasound2-plugins:i386
libasyncns0:i386 libatomic1:i386 libavahi-client3:i386 libavahi-common-data:i386 libavahi-common3:i386 libavc1394-0:i386 libavcodec58:i386 libavutil56:i386
libbrotli1:i386 libbsd0:i386 libcaca0:i386 libcairo-gobject2:i386 libcairo2:i386 libcap2:i386 libcdparanoia0:i386 libcmis-0.5-5v5 libcodec2-0.9:i386 libcups2:i386
libcurl3-gnutls:i386 libdatrie1:i386 libdbus-1-3:i386 libdbusmenu-qt5-2 libdrm-amdgpu1:i386 libdrm-intel1:i386 libdrm-nouveau2:i386 libdrm-radeon1:i386 libdrm2:i386
libdv4:i386 libedit2:i386 libelf1:i386 libexif12:i386 libexpat1:i386 libfaudio0 libfaudio0:i386 libffi7:i386 libflac8:i386 libfontconfig1:i386 libfreetype6:i386
libfribidi0:i386 libgd3:i386 libgdbm-compat4:i386 libgdbm6:i386 libgdk-pixbuf2.0-0:i386 libgl1-mesa-dri:i386 libglapi-mesa:i386 libglib2.0-0:i386 libglx-mesa0:i386
libgmp10:i386 libgnutls30:i386 libgomp1:i386 libgpgmepp6 libgphoto2-6:i386 libgphoto2-port12:i386 libgraphite2-3:i386 libgsm1:i386 libgsoap-2.8.91 libgssapi-krb5-2:i386
libgssapi3-heimdal:i386 libgstreamer-plugins-base1.0-0:i386 libgstreamer-plugins-good1.0-0:i386 libgstreamer1.0-0:i386 libgudev-1.0-0:i386 libharfbuzz0b:i386
libhcrypto4-heimdal:i386 libheimbase1-heimdal:i386 libheimntlm0-heimdal:i386 libhogweed5:i386 libhx509-5-heimdal:i386 libicu66:i386 libiec61883-0:i386 libieee1284-3:i386
libigdgmm11:i386 libjack-jackd2-0:i386 libjbig0:i386 libjpeg-turbo8:i386 libjpeg8:i386 libk5crypto3:i386 libkeyutils1:i386 libkrb5-26-heimdal:i386 libkrb5-3:i386
libkrb5support0:i386 liblcms2-2:i386 libldap-2.4-2:i386 libllvm12:i386 libltdl7:i386 liblzf1 libmagickcore-6.q16-6 libmagickcore-6.q16-6-extra libmagickwand-6.q16-6
libminizip1 libmp3lame0:i386 libmpg123-0:i386 libmysqlclient21:i386 libnettle7:i386 libnghttp2-14:i386 libnuma1:i386 libodbc1 libodbc1:i386 libogg0:i386
libopenjp2-7:i386 libopus0:i386 liborc-0.4-0:i386 libp11-kit0:i386 libpango-1.0-0:i386 libpangocairo-1.0-0:i386 libpangoft2-1.0-0:i386 libpcap0.8:i386 libpci3:i386
libpciaccess0:i386 libperl5.30:i386 libpixman-1-0:i386 libpng16-16:i386 libproxy1v5:i386 libpsl5:i386 libpulse0:i386 libqrcodegencpp1 libraw1394-11:i386 librlottie0-1
libroken18-heimdal:i386 librsvg2-2:i386 librsvg2-common:i386 librtmp1:i386 libsamplerate0:i386 libsane:i386 libsasl2-2:i386 libsasl2-modules-db:i386 libsdl2-2.0-0:i386
libsensors5:i386 libshine3:i386 libshout3:i386 libslang2:i386 libsnappy1v5:i386 libsndfile1:i386 libsnmp35:i386 libsoup2.4-1:i386 libsoxr0:i386 libspeex1:i386
libsqlite3-0:i386 libssh-4:i386 libssl1.1:i386 libstb0 libstb0:i386 libstdc++6:i386 libswresample3:i386 libtag1v5:i386 libtag1v5-vanilla:i386 libtasn1-6:i386
libthai0:i386 libtheora0:i386 libtiff5:i386 libtwolame0:i386 libusb-1.0-0:i386 libv4l-0:i386 libv4lconvert0:i386 libva-drm2:i386 libva-wayland2 libva-x11-2:i386
libva2:i386 libvdpau1:i386 libvisual-0.4-0:i386 libvorbis0a:i386 libvorbisenc2:i386 libvpx6:i386 libvulkan1:i386 libwavpack1:i386 libwayland-client0:i386
libwayland-cursor0:i386 libwayland-egl1:i386 libwebp6:i386 libwebpmux3:i386 libwind0-heimdal:i386 libwrap0:i386 libx11-6:i386 libx11-xcb1:i386 libx264-155:i386
libx265-179:i386 libxau6:i386 libxcb-dri2-0:i386 libxcb-dri3-0:i386 libxcb-glx0:i386 libxcb-present0:i386 libxcb-record0 libxcb-render0:i386 libxcb-screensaver0
libxcb-shm0:i386 libxcb-sync1:i386 libxcb-xfixes0:i386 libxcb1:i386 libxcursor1:i386 libxdamage1:i386 libxdmcp6:i386 libxext6:i386 libxfixes3:i386 libxi6:i386
libxinerama1:i386 libxkbcommon0:i386 libxml2:i386 libxpm4:i386 libxrandr2:i386 libxrender1:i386 libxshmfence1:i386 libxss1:i386 libxv1:i386 libxvidcore4:i386
libxxf86vm1:i386 libxxhash0 libzvbi0:i386 ocl-icd-libopencl1:i386 zorin-os-feedback
Use 'sudo apt autoremove' to remove them.
The following NEW packages will be installed
hplip-gui
0 to upgrade, 1 to newly install, 0 to remove and 2 not to upgrade.
Need to get 19.1 kB of archives.
After this operation, 156 kB of additional disk space will be used.
Get:1 Index of /ubuntu focal/universe amd64 hplip-gui all 3.20.3+dfsg0-2 [19.1 kB]
Fetched 19.1 kB in 0s (301 kB/s)
Selecting previously unselected package hplip-gui.
(Reading database ... 327333 files and directories currently installed.)
Preparing to unpack .../hplip-gui_3.20.3+dfsg0-2_all.deb ...
Unpacking hplip-gui (3.20.3+dfsg0-2) ...
Setting up hplip-gui (3.20.3+dfsg0-2) ...
Processing triggers for mime-support (3.64ubuntu1) ...
Processing triggers for gnome-menus (3.36.0-1ubuntu1) ...
Processing triggers for man-db (2.9.1-1) ...
Processing triggers for desktop-file-utils (0.24-1ubuntu3) ...
raymond@RTB:~$ hplip-gui
hplip-gui: command not found