Linux Mint 19 Elixir troubles

Hi all. I installed a fresh Mint 19 Cinnamon machine, Threadripper 1950x. I did the normal install developer tools and such. Then I went to elixir-lang.org and downloaded the .deb 64 bit, and did an install. Erlang 1:20.2.2+dfsg-1ubuntu2 is installed.

This is causing some issues, like

threadripper:~/forritun/elixir$ mix new myapp
** (Mix) Application name must start with a letter and have only lowercase letters, numbers and underscore, got: "myapp". The application name is inferred from the path, if you'd like to explicitly name the application then use the "--app APP" option.

and this one.

threadripper:~/forritun/elixir$ elixir --version
Erlang/OTP 20 [erts-9.2] [source] [64-bit] [smp:32:32] [ds:32:32:10] [async-threads:10] [kernel-poll:false]

{"init terminating in do_boot",{{badmatch,error},[{'Elixir.System',build,0,[{file,"lib/system.ex"},{line,172}]},{'Elixir.System',build_info,0,[{file,"lib/system.ex"},{line,164}]},{'Elixir.Kernel.CLI',parse_shared,2,[{file,"lib/kernel/cli.ex"},{line,153}]},{'Elixir.Kernel.CLI','shared_option?',3,[{file,"lib/kernel/cli.ex"},{line,113}]},{'Elixir.Kernel.CLI',main,1,[{file,"lib/kernel/cli.ex"},{line,14}]},{init,start_em,1,[]},{init,do_boot,3,[]}]}}
init terminating in do_boot ({{badmatch,error},[{Elixir.System,build,0,[{_},{_}]},{Elixir.System,build_info,0,[{_},{_}]},{Elixir.Kernel.CLI,parse_shared,2,[{_},{_}]},{Elixir.Kernel.CLI,shared_option?,

Crash dump is being written to: erl_crash.dump…done

Any help on this issue would be appreciated. Everything is straight from the box, MINT is updated, that is the only difference.

I seem to remember that you had to do some mix commands to get thing started, but I have not done so.