Hy there!
there are some issues with these steps, I would recommend you change the stac to the LTS ubuntu one, remove the emulator steps and add a script with this in it:
#!/usr/bin/env bash
# fail if any commands fails
set -e
# debug log
#set -x
cd $ANDROID_HOME/emulator
echo no | avdmanager create avd -n Nexus_5X_API_26 -k "system-images;android-26;google_apis;x86" --force
emulator -avd Nexus_5X_API_26 -no-window -no-audio -debug-init > /dev/null 2>&1 &
echo "Waiting emulator is ready..."
adb wait-for-device shell 'while [[ -z $(getprop sys.boot_completed) ]]; do sleep 1; done; input keyevent 82'
echo "Emulator is ready!"
please get back with the results! 