Development: Problem with setup

[SamuelWiet]

Great Software.
I follow the instruction in the README but fail with 'mix setup':
** (CompileError) config/config.exs:59: undefined function config_env/0
(elixir) src/elixir_bitstring.erl:142: :elixir_bitstring.expand_expr/4
(elixir) src/elixir_bitstring.erl:27: :elixir_bitstring.expand/8
(elixir) src/elixir_bitstring.erl:20: :elixir_bitstring.expand/4
(stdlib) lists.erl:1354: :lists.mapfoldl/3
(elixir) expanding macro: Config.import_config/1
I installed exixir on Linux/ubuntu/mint with 'sudo apt-get install elixir'.
'elixir --version' results in:
Erlang/OTP 22 [erts-10.6.4] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:1]
Elixir 1.9.1 (compiled with Erlang/OTP 22)
Perhaps the "mix setup"-failure is caused by the wrong Elixir version. But the README says nothing about the needed version.
Which version of Elixir should I use?

[SamuelWiet]

Finally I installed elixir 1.13.4 and now it runs locally.

[ArneVogel]

Sorry about not replying, I was on vacation.

Let me know if you encounter any other issues.